Ok, pants are one of the things that I actually pay good money to get good quality. I get Prana Axiom jeans for about $70 a pair. Yes that is a lot for jeans, but they are ridiculously comfortable. They are 1% spandex so they stretch instead of bind, plus they have a gusseted crotch so they don't... bind up (I'm sure you know what I mean). These are awesome for actually moving around in. Hiking, rock climbing, around the house construction-y stuff. Really nice being able to actually move in jeans instead of being all constricted.
Duluth Trading also makes some comfy stuff supposedly, but I haven't tried them. Look for their Ballroom (hah) line, and look for the ones that are the Flex (also 1% spandex, so stretchy). These are like $55 a pair.
You can try Prana jeans at REI if there is one near you. If not, you can return clothes on Amazon very easily if you don't like them, so buy a pair and give them a go if you want.