The Madison River, stay at The Slide Inn, and by all means, ask Kelly about the "kiddie pool" and fish it.....The Madison offers wade fishing, float fishing, scenery, large nasty fish, you are close to Yellowstone, the Henry's Fork, the Gallatin, and only about an hour and a half from Paradise Valley if you want to fish the famous spring creeks(where you will get skunked, because, apparently you never fish
)...
O'dell's spring creek is close as well....also if you are in the area of Bozeman, Hyalite creek is a nice place for small beautiful rainbows, and lots of them.....I want to go back there just typing this....
edit: if you are into still water fishing, you have Hebgen lake and Quake lake.....there is also good dining at "The Grizzly", and a fun bar scene at the titty picture place, I have forgotten the name of the place......but by all means, do not try to take home the "chick" in the men's bathroom, Grobert tried, it didn't work out for him as, she went "flat"...