A couple more Black Hills suggestions...if your coming in via the interstate from east to west take the time to stop by the Corn Palace in Mitchell SD (Its a hoot if you enjoy "roadside America" stuff.)

And if you make it to Deadwood...stop by Waterhole Number Nine (not sure if my number is correct) which has Wild Bill's death chair hanging on the wall over the door...its also the place where the summertime re-enactment of his shooting occurs and culminates in a chase of the shooter up the street and a mock trial where the audience help the professional actors by filling out the jury....lots of fun.

ITs a great little vacation area that folks really ought to do at least once.