We did something exciting or scary, depending on how things work out. We also reserved 3 nights at Threemile Campground, a USFS campground. That's on Route 14, near the east entrance to Yellowstone. No hookups, no bathrooms, just quiet. I think they said its 27 miles to Old Faithful.
It was expensive though, at $15 a night we could afford to only stay there the 3 nights
. I haven't cancelled Fishing Bridge yet, but our new thoughts are to spend June 30 at Gros Ventre, see the sights around the Grand Teton area the next day and then head over to Threemile Campground.
Maybe it's just us, but we weren't keen on being so close to neighbors in such a natural area. It's a little further out, but hey, we felt fortunate to get a spot!