This summer, my family and I are going out to Yellowstone for vacation. Our plane will land in Keystone, South Dakota, and we will have about 1/2 of a day with nothing to do, and I would like to do a semi-short, 5-6 hour full trip, hike in the area. I've done a little research and found a few trails that I liked the looks of, but I would like to know if there are any nearby trails that any of you would recommend. I would rather not have to drive more than maybe 30 miles from Keystone if possible. Thanks!