We really like Fishing Bridge RV Campground because it is inside Yellowstone National Park and has full hookups. Tight spaces, but you will have no problem with a three foot fiver. In Grand Tetons National Park we like Colter Bay RV Campground for the same reasons. It does have more room than Fishing Bridge. There is a fairly small campground somewhere on the north side of the park that has sites on a nice stream. I just can't recall the name but you should be able to find out more about it on the park's web site. Have a great trip.
