As for how long I want the pants to last...As long as possible. It would be nice to get 2 or 3 years out of them. I mean I got 4 years out of my last pair(even though the last few were a bit wet...). Pants are not something I want to be buying every year.
My old Volcoms were the only pair of pants that have lasted me multiple seasons. REI is carrying NFA stuff now so I'm going to give them a shot this season. REI has been great for buying clothes from, if they leak REI takes them back and offers an exchange or refund if they don't have what you need.
seriously, best pants i have ever owned and still do, are my scott overall pant thingys. it goes up really high so the powder doesnt get in my pants and i dont feel it when it get in my jacket. and they cost me like 10 bucks from ross, lol.
i ride mostly powder so those are my main pants but I've had some good luck with my black dot pants, which i use for park. they are like regular style pants so they fit well and no restriction in the shoulder area and shiza. those were only like 40 dollars too.
i say, look for some pants with vents and good insulation
i have a different opinion... years in volcom pants, just picked up some burton welded cargo pants... they fit and feel awesome, waayy better than the old volcoms... they were pretty spendy tho - about 240
i have a pair of Planet Earth pants from 03 i think, the matt hammer ones, never got wet, and they arent even ripping at the heels yet.
and, eerrr....i might as well rep siver, and say go for a pair of siver cartel pants.