RN, I have 2 pairs of the Swedish wool cargo pants and a pair of the whipcord. Cargo pants are almost 1/4 inch thick (blanket weight) and take a beating. Blood wipes right off, briars make no impression. I have worn them with thick fleece long johns underneath and been comfortable sitting at 20 below zero F. The whipcord are somewhat heavier than wool suit pants but much hardier. Good in warmer temps but can go colder with appropriate under-garments. I don't think you can go wrong with either, or both.
I do a lot of ground blind hunting and really don't worry about camo over my legs, just my torso (and breaking up my silhouette with hats, etc). I have three pieces of camo fabric (greenish, brownish, and snow) about 48 inches by 30 inches that I can drape over my legs if sitting. I don't carry all three, just carry the right one for conditions and location. If I am stalking, I make sure to stay within trees and my legs seem to look like stumps.