Hoppers were my favorite on the Poudre, though you're likely a few weeks past that time it may be worth a try. Big hoppers don't scare fish.
Fall I would try an attractor with a small nymph dropper. #20 or so prince/hares ear/pheasant tail.
Couple good fly shops around Ft Collins. Call them up and ask the folks that spend time on the river!
Little cut throats up high in the tributaries will it any damn thing and are a blast!
Good luck!
