Went to the sand dunes this past weekend, and except for forgetting the tent stakes, walking on the dunes in high wind, and a wet tent inside it went pretty well. Most of all the kids had fun. So, looking for another good spot for this weekend. Within about a 2 hour drive of Denver, with something for the kids ( 2 and 3 year old) would be good. They like walking, and my son loves getting muddy and wet. Was thinking yellowstone, used to live 50 miles from there, but way to long a drive from here now. Any suggestions?