I wore my prom dress to Starlight Express back in 1985:-D

Just kidding.

If you are trying to cut down on what you pack, I suggest packing lots of black. I spent a week in Europe with one carryon bag doing this. Black pants and sweaters/tops/blouses.

You can accessorize with a couple of colorful scarves.

Another good thing about wearing all black, it is the only color you can match exactly and it doesn't show dirt. You can also dress up plain black pants and a black sweater by throwing on a pair of heels, pulling your hair up, and putting on a pair of dangly, sparkly earrings.

A previous poster said to dress for the restaurant. I agree with this method, and employ it myself. Usually, that will put you in something comfortable but somewhat dressy.

You can get by with jeans, but who wants to go to a Broadway and look like you would working around the house?

GoTravel, I too basically just pack black. It sure does cut down on packing items and as you said one can change the look so easy. I just keep packing less and less and everytime think "next time I will pack less".