Kansas, Missouri - what to see, where to stop

I am planning a trip from Yellowstone to Maryville TN, and back. On the way out I plan to travel through Kansas and Missouri and would love to hear ideas about parks, hikes, sites etc on the way. Are there any particularly nice State or County Parks that you know about? I am not locked in to the highway as my schedule is pretty loose, are there any backroad routes that I should take as opposed to I70?
Any and all ideas are appreciated. Thanks
Any and all ideas are appreciated. Thanks