Soft black linen/cotton blend pants are my mainstay. They are
lightweight and don't show dirt and of course, everything goes with
black. Talbot's sells them in summer for about $40 and the Gap has
linen slacks that work ok if you pack them by rolling them instead of
folding them. If the weather gets cool I just supplement them with a
pair of tights or silk long underwear. I don't do laundry at all
when I travel - usually 2 pair of slacks and a skirt or shorts carry
me through most vacations and climate variations from 45-85 degrees.