Rapid City
The base camp for everything else, and worth a day in its own right.
Almost everyone who visits the Black Hills sleeps in Rapid City at least one night. It sits at the eastern edge of the Hills, which puts the Badlands an hour one way and Mount Rushmore under an hour the other.
Downtown
The City of Presidents puts a life-size bronze of a different US president on downtown street corners — all of them, spread across the blocks around Main Street Square. Walking the full set is a decent way to spend a morning, and children take to it more than you would expect.
Art Alley, running off Main Street, is a long-standing permission wall of murals and spray work that changes constantly. It is worth the five-minute detour.
Main Street Square anchors the downtown with events through the summer and an ice rink in winter.
Eating
Downtown Rapid has a strong independent food scene for a city its size — steakhouses, a couple of long-running breweries, coffee roasters and a good spread of family-run places that have been here for decades. Most of them are within walking distance of each other.
Using it as a base
Rapid City works best as the hub you return to. Badlands one day, Mount Rushmore and the Needles the next, Deadwood or Devils Tower on a third. Nothing in the region is more than a comfortable day trip away.