SlowMutants wrote:
Some words of advice. I'm not sure if this is your first trip to Montana or not. If it is a dedicated fishing trip, try to limit your windshield time. Pick a main river or main area and fish it hard for a couple days with one off trips to check out some other areas.
I see you mentioned Bozeman as a potential base. While Bozeman is within striking distance to may great rivers, it's really not close to any save the Gallatin, and to me the best fishing due to a combination of fish populations and scenery is the canyon section down toward Big Sky.
Apparently most on here are not fans of the west side of the park, but in my opinion this could be one of your top options during your time frame. The Firehole, the Gibbon and the Madison are all great steams. There is literally no trout steam in the world like the Firehole, and when there is a hatch on you could see a hundred fish rising. These rivers are all roughly 2 hours from Bozeman.
Another good option will be the Upper and Lower Madison. The Upper Madison is about an hour fifteen from Bozeman, while the Lower is about 45 minutes. On the lower I recommend Bear Trap Canyon. Its a wilderness area and allows you access to 9 miles of the river. Just watch out for rattle snakes.
Bottom line though is things can change and continue to check the fishing reports prior and during your trip. By late June its possible all the rivers I mentioned, save the Gallatin an Upper Madison may be to warm to fish.