I have been to Sturgis during the rally several times. Riding in the black hills is a great experience. I would suggest for a location you might want to try Custer SD. Great small town, reasonable prices, very close to Custer State Park. Nice clean restaurant in town call the Wrangler. Great buffalo sausage breakfast......
As to riding, Needles highway, Spearfish Canyon, Ride out to Hullet WY, Iron Mountain Road. All Challenging rides. Down forget to ride out to Belfusch SD, the center of the contential US, if you include all 50 states.
Other sites, Mt Rushmore, Crazy Horse Deadwood, and others to see. Take the time to ride the BadLands, the loop through the park is great and remember to look out for snakes. I almost stepped on a rattler once near the road. Wall Drug store in Wall SD is a must see. A big tourist trap but worth while none the less.
IF you really have a desire to see the west, extend your trip to go see Little Big Horn, you won't be disappointed.
Enjoy the Black Hills, they are a great place to ride.