The Snake River in Western Wyoming is very good; especially the section just going into Idaho Falls from Southfork lodge near the Idaho/Wyoming border. It's better if you float the Snake rather than wade it.
If you are willing to expand your area, the Madison River in Eastern Montana is EXCELLENT east outside of Yellowstone NP up toward Ennis on Highway 20, although a tough river to fish. It is mostly a wading river.
Also the Big Horn River near Harding, MT is fabulous. Lots of Big Browns. You can wade or float it.
We have not fished the Wind River, but I'm reading a great fictional book series about the area. ;D
Marsha~