We stayed here and went in and out of Yellowstone during the week. It is a few miles from the West Entrance of the park. We had a deluxe site with grass, porch swing, and fire pit. The playground is big and the pool is indoors. I recommend that if you stay in this area, you stock up on groceries before you get here. There are two markets in town, and they are pretty pricey.
We stopped here on our way to Yellowstone. It was nice - a lot of trees, which are hard to find at KOAs. Plenty of grass for the kids to run around on, as well as a nice playground. Very friendly staff. Be sure to bring your mosquito repellent.
This KOA was one of the better ones we visited this vacation. The staff was very friendly and understanding when we had engine trouble with our truck and needed to stay an extra hour or two while we took it to a mechanic. There were a lot of trees - something KOAs seem to be lacking. A nice breeze was present throughout the day, and the playground was small but perfect for our kids because it was shaded. It was easy to find, and it was easy to get in and out. We would probably stay here again and try to visit Bryce and Zion next time.