Not a fan of KOA but we stayed at the closes KOA (don't remember the location) because they had a shuttle bus to Mt Rushmore. We could then set up our truck camper and leave it, since we wanted to go late in the afternoon and stay to see it with the lights on. Turned out to be a good move because it was a dark and stormy night and I was glad to leave the return trip driving to the bus driver.
Since we were small and self contained they let us use a tent site to save a few bucks (had electric) and it was still one of the more expensive campgrounds we stayed at. Was nice.