Iron Mountain Road
One thing I may add...Be careful not to get onto Iron Mountain Road near Mt. Rushmore if you're in an RV (or in a hurry!). My wife and I drove from Charleston to Seattle a couple of Augusts ago in her conversion van and one stop was Mt. Rushmore. At the welcome center in South Dakota, the ranger warned us NOT to get onto Iron Mountain Road if we were in a large vehicle or if we had a timeframe for the day's travels. We thanked him, then promptly took a wrong turn out of Rushmore and found ourselves on it after all. It is a winding, switchback road up and down the mountain (though it IS beautiful!) that can get crowded, but there were also two or three square tunnels carved through the mountain where our relatively small van barely made it through. The bikers (there for Sturgis) all stopped to watch, clapping after we made it to the other end. After we were finished, we agreed it was actually fun, but it took us about 1.5 hours end to end because of the traffic. I agree that Mt. Rushmore was worth it, as were our side trips to see the Badlands and Devil's Tower.