my wife and I are from the Portland area and lived in Rapid City for four years. We have been back many times. We almost always used I84 to I80. We have done that trip in two days but generally with an RV took three. The Black Hills have changed over the years and has become very commercialized. Lots of touristy stuff now but still an amazing place. Deadwood was ruined by the casinos but Boot Hill is still the same. Crazy Horse is taking shape but expensive to visit. We generally stay at the Ellsworth AFB Fam Camp but there are lots of campgrounds to chose from in all price ranges. If we can't get in we use The Rapid City KOA. Close to stores and eating places. As mentioned the Sturgis Bike rally is in early August and the whole place area turns into a big parking lot. The Badlands and Wall Drug are worth a visit but in the park are more natural things to see and do. Also a cave tour close by. You won't have any problem using your time.
