Guess it depends on how you feel about the park, but personally Jackson Hole and Yellowstone would be a serious hassle in my mind. I grew up in the area, so my view may be quite different than others. That route from Livingston to Missoula would be interesting, but man that's long. I'd almost rather exit Yellowstone west back into Idaho and wander up from there.

Were you planning to take Hwy 28 from Rexburg up to Salmon? That's a long ride without many services, but you could camp anywhere you want. I'd love to do that ride. I remember driving down 28 at about 120mph in high school. There's ghost town near the summit, named Gilmore.

Great sounding trip. Post plenty of pics for us. Okay?