I absolutely love the Tetons - but I'm not between the ages of 5 and 12. The Tetons are known for their beauty. Yellowstone is known for its moving parts. Lots more things for your kids to see, like geysers, bubbling mud pots, the Yellowstone river and the upper and lower falls. And a lot more wildlife. Save the Tetons for the second trip when your kids can enjoy it. You can't even do Yellowstone in 5 days, but it will whet your appetite for a return trip.
In the Black Hills area, the Badlands is a drive thru, but you can spend some time in Custer State Park driving the wildlife loop, driving the needles highway, and feeding carrots to the herds of wild burros, and check out Mt. Rushmore as well as Crazy Horse.
You'll all want to go back in a few years. So much to see and do.
