We did this trip last year with the wife, myself and 12yo son. We picked the hottest day and did Wind Save and Jewel Cave in same day. We stayed at one of the lodges in Custer State Park which was awesome on its own, and did the Buffalo dinner / cookout.
I saw nothing else around Devil's Tower. Cool to see but not much besides that.
Didn't gamble in Deadwood but it seemed like your standard low level casino / slot machine parlor.
Once thing I wished we had done was the tour of the gold mine in Lead. Stanford Research Laboratory has a museum and several different tours.
The ICBM main attraction was under refurb when we were there. Would have liked to spend more time seeing it if open.
The AFB there has some awesome aircraft on display.
"The absence of the word accountability is not the same as wanting no accountability" -unknown
"You can never go wrong by staying silent if there is nothing apt to say" -Walter Isaacson