[JRTJH]

While in Hill City area visiting Mt Rushmore, I'd include a drive through Custer State Park, Crazy Horse Monument and a 2-3 hour drive through the mountains around Mt Rushmore. There are tunnels through the rocks that are barely wide enough for a modern pickup to fit, certainly DON'T attempt to tow through that road, but for us, was a "must see" event.

Wall Drug, while a commercial (money making) site, is definitely worth a couple hours as is the Minute Man Launch Site which is nearby. If you're into aircraft/aerospace history, Ellsworth AFB has an excellent display of vintage USAF aircraft and some "in depth" local military history.

While in Hill City, you can do a walking tour of the "downtown area" to view "life size statues" of all the presidents. They are placed throughout the town center and it can become an "Easter egg hunt" type event for kids as they search for the next statue.

For us, if we'd have only stayed "one night as a drive through" we would have been very disappointed at all we would have missed because of the lack of time in the area.