Highly recommend The KOA at 12620 Hwy 244 Hill City. Stayed there as our base camp for six nights last summer. Its about five miles from the Mt Rushmore entrance. KOA there has actives for kids of all ages (pool, horse back riding, snacks bars, movies, etc.) Last year there was an onsite rodeo.
Central location for Hill City, Rapid City, Sturgis, Elsworth AFB, the bad lands, Custer State Park. You need to tour Mt Rushmore during the day and return for he evening program at the amphitheater. Our service men and women are honored. No entrance fee as it's a national monument but parking is $10 and good for in/out for seven day. No shortage of activities in the greater area.
Wind last year destroyed several awnings on RV's and popup canopies. Suggest you only have them out when at the RV. Have fun!
Olybldr
Olympia, WA