Nona1 wrote: "Ackisander, I don't think anyone was suggesting they only have one pair of trousers (of whatever type) for the entire two weeks?"

But previously she wrote: "Jeans don't really show the dirt so unless you have some sort of accident, you don't need to wash them on holiday. I'm quite happy to wear the same pair for a week at home (or maybe I'm disgusting, but I don't think it's uncommon)."

So okay, a pair for week 1 and a pair for week 2. Still . . . . Maybe women are different, but I don't want to sit next to a guy who has worn the same pair of jeans for a week.

Some ideas for you -

Wear your heaviest clothes on the plane. Jeans, a sweater, shirt, T shirt, a jacket. That way, they won't be in your carry on. Remove or add as appropriate.

Darker colors show dirt less.

Plan a laundry stop mid-way through your trip. Check in advance whether your hotel in Seville or Granada offers laundry service. Could be expensive, but worth it. Or, ask at the hotel or otherwise find a laundry that will do it for you. Or, for an adventure, find a laundromat and do it yourself.

At the risk of destroying Europe's ecosystem, I have thrown dirty clothes away there and bought new clothes. No discernable effect so far.

If, for the sake of discussion and assuming that you gave a fiddler's fart about what someone says about your clothes, you want to look a bit sharper you should bring decent shoes, mix with darker blue jeans and a decent polo shirt. Or wear a non-flashy T shirt with a smart sports coat. You got tons of options, actually, including smart looking trainers that don't have be "phat" bright white Nike's to be comfortable.
The Southerners are usually better dressed (or better said: more dressed) because they don't see the necessesity to run around half naked just because the temperature is above 25C.

And, as I am going to leave for Barcelona tomorrow, what on earth should I do with my 501s now that I know that we don't wear them in Europe ;-)

My comments on choices of clothing items had nothing to do with fashion and what others wear and everything to do with travelling light, with a carryon as the OP mentioned, and (may I suggest) hygiene, as in washing one's clothing after a couple of wearings. "Khaki" referred not to a color but a fabric, easily rinsed out and able to dry in a reasonable time. But if, like someone above, clean clothes are not a concern then, by all means, jeans.

I'm currently in the beginning weeks of a 4 month trip with a carryon size bag in the tropics. But will finish in Rome in December. In the bottom of my bag is a pair of jeans which I'll use then. If you are an adept packer, as I have become, then you can take a bit of everything in a small bag and dress as the spirit moves you. But since you ask I assume you're not quite sure yet andare asking for practical suggestions. Hence mine regarding the ability to be tidy and clean as well.

DH and I do carry on -- one rollerbag and one personal item -- and he has to bring cpap and two laptop computers.

Last two trips (March and August) he brought

Jeans -- dark, well fitting, comfortable--worn on the plane, with a belt.

Dark Grey Dockers -- packs them -- only worn twice (evening) on last trip.

4 botton-down long sleeved shirts -- striped and solid.

Tshirts, undies, long underwear to sleep in.

August trip -- Navy Blue Blazer from second-hand shop, grey Scottevest windbreaker.

March trip -- argyle sweater and Burberry trench instead of blazer and windbreaker.

Wears his "good" (dark brown/leather) shoes; brings New Balance for long walks.

Me: black slacks (warm in winter, light in summer), 1-2 light skirts, tops, jeans in March, boots in March, trench coat in March (Scottevest) Sandals and closed walking shoes and flats in August trip.

We washed once (laundromat) end of first week. We hang out clothes we will re-wear every single night to air out. This practice is of tremendous help in getting through the week fresh

I wash the undies and my lightweight/fast dry tops in the sink.

You can do it!

Just to add -- March trip was Italy; August trip was UK/France/Belgium.

We stayed in Navy and Army clubs with dress code and the button down the front (dress?) shirt and blazer were magic, whether with jeans or the dark grey Dockers.

<<Your wife doesn't need skirts but should have a pair or 2 of nice pants for evening.>>

Just to clarify, mamcalice, it wasn't about dressiness. I like skirts for traveling because i find them more comfortable. Skirts aren't just for show, you know! ;)