More thoughts for your trip: Some of the fantastic views in Yellowstone are on smaller, one way roads restricted to motorhomes and trailers. Example, the "Grand Canyon of Yellowstone" and a warm water swimming area along the river. Renting a car or van for travels through Yellowstone really seems like a good idea. If you can fit it into your schedule go to the Bar-J Western show in Jackson, Wy.
Glacier National Park has a great Red Bus Touring system operated by the park which will take you up the Highway To the Sun and around the park. You could rent a car there, but you can do just as well with tourist transportation. If you go into Canada, be sure to take the family to Buffalo Jump, a Canadian museum and display about early Indian buffalo hunting.
Again, Have Fun.
