Montana it is! Oh yea...where?

Thanks hermy, as bad as I want to see both Yellowstone and Glacier, I have to agree that they should be exclusive destinations, especially since we only have 4 days to explore. A couple of other posters have suggested the Bozeman area as well, so I plan on on doing some extensive research on that area. I also agree that we want to spend more time doing and less time driving. So tell me, other than the ghost towns, which we definitely want to see, what else is there in say a 50 mile radius? As I mentioned previously, we like hiking, waterfalls, wildlife, and gem/rock hunting. Also any RV park recommendations would be helpful. I would prefer full hook-ups since there will be 5 of us in the camper.
As far as having to go back for a second trip, that's a good problem to have, we've already discussed spending at least a month there when we retire. But for now we'll just have to settle for 4 days.