I can highly recommend the Delta-01 Minuteman launch control facility in South Dakota, near Badlands National Park. Only 6 visitors at a time, so tickets are hard to come by. But it's an eerily awesome facility. Also the nearby visitor's center and missile silo are cool. But the launch control facility is the star of the show.

Also Trinity is worth visiting, although both a pain to get to and only open 2 days a year.