I think your idea to bring skirts is a good one. A skirt will wear much longer then pants without having to wash them.
Instead of using one large toiletry bag, I use several smaller bags, they fit into small spaces in the suitcase, if something spills it doesn't ruin everything. Also, each bag is designated for a specific use: A small first aid kit with band-aids and a sampling of medications for one time use(pain, imodium etc), hair and makeup in one, laundry stuff, small voltive candle, and a couple of cones of incense in another. Since I pack plenty of moleskins, a pumice stone and foot creme, foot care has it's own bag too.
I don't like to buy travel sized shampoos etc. Instead I have little bottles from REI that can be reused over and over. They have good lids that stay on and because they're made for backpackers they don't wiegh much.
The only travel sized thing I buy is hair mousse and it's ironic that it's one of the hardest things to find in the travel sections.
Have a wonderful time.

I've tried lots of different day packs over the years but my favorite is the messenger bag by Baggallini, available at ebags.com for $35 with free shipping. It's lightweight, comfortable, has special places for a cell phone and water bottle, and holds a surprising amount of stuff. I just gave one as a gift and she raved about it, although she uses hers as a city purse. Read the customer reviews on it at ebags.com.

Baggallini also makes a 5-currency zippered bag that fits well into the messenger bag. It sells for about $15 and is very handy. On our last trip, I had euros, US dollars, Swiss francs, Norwegian and Swedish kroner. That little bag made my life a lot easier! I bought it from ebags.com but they no longer carry it. Try thesavvytraveller.com.