+1 on the Arcteryx Gamma LT pants- I wear them almost year round also.
A little on the pricey side, but they have been through 2 years and still look new.
I also have relatively big thighs and they have plenty of room
The fit is nice and they have a little elastic so you can move up high steps without a problem
They dry quick if you get rained on
They don't show dirt, although if they ever make them in tan, I'm buying a pair
The grey color is the lightest they have, but I have worn them in 100 degree days without too much trouble.
They have also kept me comfortable (with a baselayer) on a windy, cold night- temps in the 20s and 30s.
The pockets are nice and deep, and zippered so stuff does not get lost
Although the zippers are the one thing i'm not thrilled with on the front pockets- I like to stick my hands in my pockets and can't do that without putting the zippers down. The right leg pocket is nice- holds first aid kit, meds, phone, compass.
Still my favorite pair of pants after two years.