2x Fort Welikit in Custer. Stayed there the first of October with the daughter and granddaughters. The girls loved the fort and the deer and turkeys wandering the campground. Staff and facilities were great. I would stop at Devils Tower on the way to SD. If you have kids, 2 things I would recommend are the Mammoth Dig in Hot Springs and the fish hatchery in Spearfish. The Spearfish City campground is next to the fish hatchery and is a nice campground we have stayed at before. Wall Drug is a couple hour stop. If you not hiking, the Badlands is a half day visit. We enjoyed the trip so much we want to go back in the summer with better weather.