We're in the beginning stages of planning a summer family vacation to the mid-west this summer. Looking for your tips and suggestions. What to see, what to do, where to fly in/out, etc. Kids are 13, 15, and 17. Thought about flying into Denver and trekking out from there. Some things on the list of possibilities already are Pikes Peak, Grand Canyon, Mt Rushmore, and Yellowstone. Planning to spend about two weeks. Thanks!