We'll be staying in Hill City for the duration of our four-day visit. I'd like to visit Devil's Tower. Would it be better to make a day trip out of it on one of those four days, or to take a longer route back to Denver and see it? I really don't want to drive anymore than I have to, btw. It will be just me and my 12-yr old son - so stopping at casinos is not on the agenda.