We just hung out in the Black Hills between Bear Country (traffic nightmare), Reptile Gardens and Custer State Park. We opted out of doing the Flintstone Village at Custer because they wouldn't let us mini golf-we did however mini golf at another location and I beat my wife by one stroke. At Reptile Gardens we spent time in front of their 1939 World's Fair Funny Mirrors and I visited with an old friend-Methuselah-at 127 years old it doesn't appear my riding him when I was 8 did much damage-although they don't let the kiddos ride him anymore. He's been with the park since the 50's. The kids pretended to be prairie dogs too.
Custer State Park in South Dakota is great for seeing herds of bison, wild burros and antelope. We enjoyed a quiet supper at the Blue Bell Lodge and then fireworks over Custer from the hotel parking lot.