A little bit of a drive, but its this humongous butte in the middle of nowhere. There is a asphalt walking path around the butte for great scenic pictures! I've seen climbers on it, so if your an avid climber check out the website to get permission.
If you want to experience things unique to our area of the country then Devils Tower is another "Must Do" on your list. Drive up through beautiful Spearfish Canyon to get to there for another gorgeous drive, then return through Vanockers Canyon to be overwhelmed by nature's beauty again.
A beautiful drive, Devils tower is just 45mins away from Gillette. It wonderful for a stroll, a hike, or some challenging rock climbing!!