The Black Hills of SD. Maybe Hill City and/or Custer. The shopping isn't great, but you have the Mickelson Trail through both towns. Mt. Rushmore and Keystone (where there is some shopping) is a pretty quick drive from Hill City. From Custer, you can drive the wildlife loop through Custer State Park. And no visit to Custer would be complete without a ride or drive of Needles Highway.
Note that in Hilly City there is a shuttle service that will take you to various points along the trail so you can ride back. One of my favorite sections of the trail is between the Rochford area to Hill City, or even as far north and the Engelwood trailhead. South of Custer is also nice. Between Hill City and Custer is probably the least interesting, although it does pass by the Crazy Horse Memorial.