The only RV park reservation we made ahead of time was for the Grizzly Yellowstone park in West Yellowstone, MT. We did this about 3 weeks before we left, and it was the last spot they had available. As far as getting a spot inside Yellowstone forget about it. We were only a quarter mile from the west entrance, so that was fine.
I'd ridden through part of Yellowstone in 2008 on my way to the Sturgis motorcycle rally, but had only seen a small part of it. We had 2 days, which is still not enough time, but we did hit some of the attractions. And Becky was very excited to see the buffalo.
We stopped along the Madison River for our first photo op. It soon became clear to us that if we stopped everywhere, we would never make it through the park.
Of course we had to go see Old Faithful, and we got pretty lucky. After some time finding a place to park, we made it to the boardwalk 5 minutes before the eruption, which averages 91 minutes between each one.
More sightseeing: