For our fall trip in 2014 we traveled to Yellowstone National Park, and we camped in Madison Campground, which is near the west entrance of the park.  It is a nice park with plenty of camping sites available for both the RV camper, as well as the tent camper.  I would suggest that if you planning a trip to this campground that you make reservations ahead of time.  We notice every morning that the campground full sign was down, but by 5 PM or so, it was back up again.  So this a very popular campground, especially late season as it is one of only a handful that are still open.

The blue arrows on the map below indicate the location of the photo, as well as the direction that it was taken.  The map of the campground below is from September of 2014.  If you have any questions about the campground, please follow the link below to the official website.