(A couple years ago my family moved from the East Coast to Washington State. Thanks to this forum, we were able to plan an excellent trip through the Black Hills, Yellowstone/Grand Tetons, and Glacier NP.)
We're moving this summer from Washington State to central Kansas. We've already done the "northern route" (Montana and Wyoming), so I'm looking at going south through Utah and Colorado (82, 84, 15, 70). My kids are four and six. Time will be of the essence (looking to see the highlights, but not spend multiple days in any one location).
We love mountains and hiking. We love anything kids enjoy (water parks and aquariums and children's museums).
Any suggestions on must-see things to do or see?