I snagged a set of KUHL pants with a -40% coupon at REI a few yrs back. Mine at least...were NOT field pants. Did not hold up at all.
Take a look at ARBORWEAR. Comfy, gusseted crotch.
DULUTH TRADING fire hose pants... currently -25% off with the code FESTIVE. Great pants, comfy, gusseted crotch, and hold up like iron. Also come in flannel lined!
KITANICA is expensive, made in USA but the best warm weather field/range pants I have found. Well designed and built , comfy, tons of pockets and tough. Sign up for the deals and occasionally they have decent savings.
FILSON THE Mother of traditional field clothes. "Buy once/Cry once" pricing unfortunately. Their wool vest and wool pants are a Montana winter staple.
Karhart.........For the bucks...good stuff. Heavily discounted at farm and Ranch stores.