I did the exact same trip about 8-9 years ago. Half motel and half KOA cabins. Mt. Rushmore was a lot more interesting than I thought it would be. We were there on 7-4-02 and they were worried about a terrorist threat on the holiday. There were armed soldiers about every half mile at least 5 miles out from Mt. Rushmore. They actually brought a bomb sniffing dog inside my conversion van and looked under it with a mirror.