My Favorites
1. Badlands National Park

Badlands
2. Jewel Cave National Monument

Lava
3. Mount Rushmore

Mount Rushmore
4. Custer State Park

Sylvan Lake
5. Crazy Horse Memorial

Crazy Horse
Other Considerations
Sioux Falls

Sioux Falls
A nice pass through or stop for a meal in the small town of Sioux Falls and be sure to visit its waterfall.
Corn Palace

Corn Palace
Worth a stop along your drive to/from Mount Rushmore. Parts of the building are actually made of corn! Not the structural parts of course. The murals on the outside and inside of this center are impressively designed out of different colors of corn.
Wall Drug Store

Wall Drugstore
Another stop on your road trip, this famous drug store is pretty big and has all kinds of things including Western clothing, drugs (not the illegal kind), outdoor items, and a cafe. Good place to stop, stretch your legs, maybe have a burger.
Devil's Gulch

Devil’s Gulch
Hideout of the legendary bandits Frank and Jesse James.
Deadwood
Home to Wild Bill Hickock and basis for the show Deadwood. Small, quaint town worth driving through if it's on your way.