we stayed here
http://www.custersgulch.com/last July. It is between the town of Custer and Custer State Park. Sites 19-28 are the best in my opinion.
There is plenty to see and do in the area and your week will be busy if you try and do it all. Mount Rushmore is a must see but we passed on Crazy Horse since you can get a pretty good look at it from the highway.
We enjoyed visiting Deadwood, seeing Wild Bill Hickock's and Calamaty Jane's grave sites. We also left a couple of $$ in the casinos in the remodeled old buildings downtown.
Take a day trip to Wall Drug and do the scenic loop through the Bad Lands National Park.
Another day trip to Devils Tower in Wyoming was nice too.
We spent quite a bit of time exploring Custer State Park, make sure you take a tour on the wild life loop road.
Needles Highway is a very scenic drive through the mountains as well as Iron Mountain Road. The tunnels look narrow but you'll fit (barely!!).
They do have fireworks at Mount Rushmore the week end of the 4th of July. Make sure you check out which day they are shooting them off and arrive early if you go.
We really enjoyed our trip and I'm sure you guys will too. Have fun and safe travels.
Phil