I love fishing the Big Horn but I hate to nymph. I use a 7 wt with a sink tip line and size 4 wooley buggers between hatches and fish drys when the fish are looking up.

Michael Mastrangelo at Fort Smith Fly Shop and Cabins is a top notch guide. His wife Ellyn is an awesome cook and their cabins are a great value.
http://www.flyfishingthebighorn.com