Yes, it is too much.
You can rinse out your undies.
Take only what you can heft, EVEN if you are on a tour--you still have to handle your "stuff".
You can not bring enough clothes for 3 weeks so just get over that!!

Fill that 28" suitcase with stuff and see if you can carry it up 3 flights of stairs and then decide whether you want to do that every other day for 3 weeks.

Good points - I don't plan on a different piece for each day but I don't want to wear the same very few items is what I meant. What size would you recommend? First time traveller here - that's why I'm so clueless

I travel with a 22" suitcase and a small carry-on case.

I also have a 22" suitcase that expands. I don't like that one because I put too much stuff in it, and it is too heavy when I do that.

I always bring pants and tops that I can mix and match--usually three pairs of pants and 5 or 6 coordinating tops. I bring one dressy but easy-to-wear outfit. On the plane, I wear the items that take up more room--a jacket or sweater and also walking shoes. I bring sporty sandals and dressy sandals, which don't take up much room.

I have traveled for 9 weeks (four of the weeks were at a language school) with this size suitcase.

I have traveled with a larger suitcase and regretted it. The last time was in 2000. After that trip, I put that lovely suitcase in the closet and haven't taken it out since then. I don't recall whether it is a 24" or a 28," but whatever size it is, it's too big.

I like Jean's suggestion.

I use a 21" expandable bag for 3 weeks and either a small (and I mean small) soft-sided duffel or a day pack.

Bring a few pashminas or shawls and some kitschy costume jewelry to vary your look. There are shops in Europe.

You'll want comfy cloths to wear since you'll spend lots of time on the bus. Carry your warm jacket.

I don't know anything about bus tours, so am clueless about that myself, but I usually travel with a 19" or 21" suitcase for however many weeks I'll be away. If I can't lift it up over my head easily or haul it up onto a bus or train, it doesn't come with me.

I've never gone anywhere, even for a couple of months at a time or more, with a 28" suitcase. No one in the places I'm traveling will ever see me again or even be the slightest bit concerned with what I'm wearing except maybe my friends in foreign countries, so there's no need to try to create "impressions." On a bus tour where you're being rushed from one place to the next, all the more relevant.

Take some plastic bags to store damp/wet things. 3 pair of pants sound about right but do take a pashima besause the plane may be chilly. Tops..tees of course and a sparkly one for any evening things you might do. A 28 inch is way too big, heavy and cumbersome. April may be cold in your travel neck of the woods. It certainly was last year but who knows. Take a squall/wind/rain jacket, a sweater, dark pants, jeans as you probably can't live without them. Nowhere that you seem to be going will you find people dressed up, but you will be naked without a scarf or 2. Cut out the extra shoes, flats will be dressy enough if you dress up at all. You will look just fine. If you use a face cloth then bring your own as you won't find them in european hotels. Contiki isn't known for over the top classy travel types is it? Casual garb will carry you through.

I'll have no time for laundry so I have to bring enough clothes to last me 3 weeks without wearing the same few items over and over and over again.

I think it is worth looking at the reasoning.

[some kind of implied reasons] -> no time for laundry -> bring enough clothes [without laundry] -> 28" luggage.

The implied reason is that the clothes don't have time dry with a sequence of one night stays? What if the clothes dry overnight? then,

clothes dry overnight -> time for laundry [at your accommodation] -> bring less clothes that mix and match -> needs only a 20-22" luggage?

Is there such things as quick dry clothes? Yes, lots and lots of them for tops, bottoms, and undies. Companies such as REI, Columbia Sportswear, Arcteryx, Exofficio, etc, make many such kind of clothes. If you don't have option of building a collection of such clothes, select items that dry fast. These are usually high tech materials. Cotton items don't dry fast. I bring a clothesline and inflatable hangers to have places to dry laundry in my room.

Go to your local luggage store. They usually have individual packets of Woolite that you can use to wash clothes out in.

If you can't find it locally, www.minimus.biz should have what you want.

Also take a portable spot remover. Tide, among many others makes a decent pen-like spot remover.

I personally use a 21" suitcase, and have been as long as 6 weeks on the road with the one suitcase. I also have a trusty Le Sportsac day pack that I use for everything.

I always travel with either a 60 litre backpack OR a decent sized day pack and a tiny suitcase on wheels (which I can easily pick up and carry if needed) which combined give me about 60 litres. I've travelled for months with either of these two options. Luggage is just a drag.

Hotels may hate me but I've never used a laundromat while travelling. I just wash in the sink, roll in a microfibre towel and hang to dry. Every now and again something isn't perfectly dry when we leave but I either wear it slightly damp or pack it and hang it out at the next place.

Lastly, don't go with a full wardrobe because then you have an excuse to buy a few things along the way. And, yes, scarves are a girl's best friend when travelling. Two or three light scarves can change a black t-shirt instantly.

I've never met anyone who wished they'd taken more luggage.

There is no way you can carry 3 weeks worth of clothes, so get that idea out of your head.

Plan on rinsing out undies, bras, socks and tees at night. A micro fiber towel is your best friend.
Make sure everything you take will mix and match and layer. You do not need jewelry, tons of make-up or hair products. You're going to be on vacation, relax!

Put out everything you think you need on your bed, pack it and then carry your luggage up and down about 3 flights of stairs. Yes, you will have to do this on your tour. Not all hotels in Europe have elevators and you'll need to get your luggage through the airport and on and off the bus each day.
People in Europe use soap, deodorant, tampons, etc., just like the rest of the world. You can pick up what you need.

You can carry 3 weeks worth of clothes only if you have a set of matching luggage - 3 or 4 pieces - like they used to have on transatlantic ocean liners.

Since it's Con Tiki assume you are young and your clothes are small and easily squishable. they will move your bag - but that doesn't mean you need a 28" - which you probably could not pick up if full.

I use a 24" plus a soft-sided carry-on - for toiletries, camera, books and one change of clothes. That is plenty for a 3 or even 4 week trip. But I do have the hotel do laundry (undies) on the way - plus anything else that might get a spot or stain. Make sure things all can be mixed and matched. Do not bring a lot of shoes you can't wear - 2 pair comfy walking shoes (wear one on the plane) and one pair for evening (ballet flats or low wedge - since a lot of streets will be cobblestones and heels are fatal).

One key item to note: simplify your beauty routine. On a tour you typically have to have your bags in front of your door by 7 am and be on the bus by 8 am. So you don;t have 30 minutes to foof your hair or 20 to do make-up. You should have the whole thing - including shower and washing hair - down to no more than 30/35 minutes - or you will regret it.

We were away for a month and took carry on luggage only. I have travelled extensively and this was the best decision I have ever made!!!

Years ago, we traveled as a family for a month in Europe and each of us took a 26" suitcase. Nuts! We go nowhere now, for any length of time, with more than a 20" suitcase.

I generally bring those little packets of Tide that you can get at your grocery store in the miniature department, but--and I will be a trifle indelicate here, I wear underpants for two days, with a panty liner for the second day. That feels perfectly clean and it means that I don't have to wash out panties as often.

I second the idea of bringing a plastic bag, preferably a sealable bag, for anything that doesn't dry completely over night.

I remember the trip I took with my sister when we each took a larger suitcase and a small suitcase. What idiocy! We wanted to change rooms in our hotel in Munich, and the proprietor said we had too much luggage--that it wouldn't fit in the room.

As a chronic seasoned overpacker, we travelled last year in Spain for 19 days with 8 hotel stops. We used the trains but lugging the wheeled 26" split duffel still weighed 48 lbs. We will never travel w/ that much again anywhere. A 22" carryon will more than suffice. You will have soap, shampoo & body lotion & hairdryer at hotels . Only bring thin clothing that can be layered; bring/wear one fleece hoodie; bring one packable (into tiny sac) down vest; wear your jeans and pack 'performance' pants for day trips (stated above in sports shops); silk shirts or thin cotton; merino baselayer in shortsleeve & long will see you. Ballets for dinner/evening, comfy sandals, and waterproof sneaker/hiker type (NorthFace or Merrell). Stick to black w/ khaki & gray w/ few color accessories. Carry a large tote on plane and pack a smaller nylon tote or small crossbody (e.g., Baggalini brand). Download travel info or photocopy relevant pages from each site, and toss as you go.

Leave the "lots of shoes" at home. You need a good sturdy pair of walking shoes and a pair of comfortable slightly dressier shoes.
Don't try and haul along the whole shoe cupboard.

I'm an inveterate overpacker and agree that a 28" bag is too large. But, a carryon would be too small (for me) for three weeks. And, since you are on a bus tour and your bag will be handled for you, a 24-25" should be fine. (You won't have to lift it overhead.) If the bag is expandable, save that for what you may purchase along the way.

Agree with simplifying the wardrobe. Forget "outfits". Everything must match everything else. I prefer a polartec with hood to a pashmina. Make sure everything you pack fits and is comfortable and that you enjoy wearing it enough to wear it several times over.

You should also think in terms of the ubiquitous layers, since weather in April is so variable. A water/windproof outer layer that's roomy enough for a layer or two underneath is essential.

Unless there are dressy activities planned, don't bother with dressy shoes or clothes. A pretty blouse with a sweater in your favorite/most flattering color is dressy enough. You could add a silk scarf.

Bring only jewelry you wear every day. You don't need more than that.

Same goes for cosmetics and toiletries. Don't bring anything you "might" need that you don't use every day. And, don't bring more than an adequate supply. Pour shampoo, conditioner, body wash, etc., into small containers and see how long that lasts you at home to determine how much you'll need. And, dispense only what you need - not a handful when far less is plenty. Don't pack full size products of anything you won't use up. If one small bottle isn't enough, pack two or three, tossing the empties as you go.

Plan to do a bit of hand laundry at destinations where you'll be for more than one night. Pack tops, underwear, that will dry overnight. (Test them at home.) If you roll items in a towel, they'll dry faster. But, towels are often not plentiful (or don't dry in time for morning use). I don't care for the inflatable hangers, rather pack a plastic hanger (or two) with skirt clips and a swivel hook, so you can dry a pair of slacks and a top on the one. A microfiber cloth is handy for removing stains, lint, etc.

Pare down the makeup! Most of your fellow travelers will be wearing little or none. Bring the bare minimum. You don't need all those colors or more than one of anything (eyeliner, mascara, etc.). (And, most of the time, you'd have to get up to early to have time to apply all that.) No one will care (or even notice) if you're wearing more or less. Same goes for hair products. I discovered long ago that my hair actually looks and holds up better throughout the day without them. Bring only what is essential. Best bet is "wash and dry" hair style.

One thing I do pack plenty of is pharmaceuticals. Anything you regularly use at home. And, I've learned to pack cold medications. I've been on more than one tour where a cold spread through the bus and no one had any cold remedies and it was quite a while (or never) before there was anyplace to purchase them.

For sure, you'll get tired of the same clothing by the end of your trip. But, hauling more is just not worth the aggravation (and you surely won't miss all the extra cosmetics and products).

Believe me, at 19, you'll look fabulous with very little "stuff", and have a much better time not worrying about all that.

A 24 or 25" suitcase will fit you needs. I do tours of up to 16 days and do not do laundry. Underwear does not take up much room. You can fit it between other things. I can fit in that size suitcase 3-4 pairs of jeans and a pair of dress pants and at least 8 tops so I can wear them 2-3 times. I also bring all the hair and makeup stuff that I use every day.
Get a folding toiletry bag for toothbrush, paste, lotion etc and I put it right on top of everything before I close the suitcase. The makeup bag I keep in my carry on back pack.
Hairspray and gel, mousse etc fit in between clothes. Just remember to put these things in plastic ziploc bags so they don't leak.
My suitcase does not weigh more that 35 lbs and I do not mind checking it.
It helps that I am an early bird because I am up at least an hour before the wake up call. Takes me an hour to get ready and I cannot shorten it. If you like to sleep until wake up call you will only have about 30 minutes before breakfast to get ready.
Hope this helps with a different opinion from most of those above. I like to take what I know I will use and not worry about things. And I have packing down to a science after years of experience.
One more thing don't bring a hairdryer, most all hotels have them in the room. If they don't the front desk will have one.

Dry cleaner plastic bags are thin, light, and damp-proof. They let you pack partly dry sink laundry to finish drying at the next stop.

Pack LIGHT but pack RIGHT :

http://www.nytimes.com/2010/05/06/business/06PACK.html?_r=0