It felt like sleeping in truck stop
Rushmore KOA at Palmer Gulch was our first experience at a KOA. We thought that having lots of amenities would be beneficial. However, we weren't given an opportunity to choose our campsite and ended up in a tiny pad on the end of a long row of giant RVs. Our car didn't fit on the pad without straddling the firepit. Even then we feared a tight-turning RV could ram our car.
The check-in process was amazingly easy and we were kindly directed to our spot. We were far from any trees but could make out rocky prominences on the horizon. The pad was very level, for this we are grateful. We had no trouble with hookup.
Palmer Gulch is in a canyon so there was no cell signal. Even with a booster, we only got up to one bar. The local WiFi was better than nothing. I could check emails, though they loaded over minutes each. It was impossible to watch any television or do much web surfing, especially during the evening when most people want to do these things.
Taking a walk meant passing dozens of smoking fires, not getting into nature. I'll grant that it could be fun if you have kids, but most of the shops and activities were shut down (Covid? or season?).
We just wanted a nice quiet place to spend out SD vacation. We were out and about during the day anyway, but rigs pulled in right past us until after 11 PM. Those diesels trucks and Class A's can be very loud when you're trying to get to sleep.
We left a day early because we didn't enjoy staying any longer. They were very professional and accommodating with one-night's-stay refund.
I would have preferred parking under a tree somewhere, though he haven't done that yet. There are many RV parks in the Black Hills, but most that we saw were similar to the KOA (tightly packed units). The State campgrounds look more promising and, if we go back, we might try to stay at one of them.