Some of my favorite western rivers for fly fishing…
Smaller rivers are also the best way to learn and understand what fly fishing gear you will need starting out. I suggest waders, wading boots a vest or fanny pack as well as your fly fishing rod and real.
The Green River in Flaming Gorge Utah.

This river is a great larger river once you have spent some time and feel comfortable in and around the smaller rivers. This is an excellent one to up your game on. You can wade fish this water or take a raft or drift boat down it. On a bigger river there are bigger fish so I recommend that you have learned some good fly fishing knots. You will find some excellent fishing for all levels of fishing here. Plenty of dry fly fishing as well as terrestrials, streamers and nymph fishing.
The South fork of the Snake River in Idaho.

This is a great river to float with a drift boat. This is also a larger river and you definitely need to be aware of the strength of all waters but especially the larger ones. I usually have my best luck using dry flies and streamers. I like to fish this during the colder months, however, I have made this trip during the winter to find that there is no access available.
The Salt River located in Wyoming.

This is a fantastic medium size river. It is very versatile as it can handle a drift boat in most stretches but is also great for rafts and wade fishing. As you can imagine most the fish aren’t of great size but I have seen some really impressive cutthroats.