When I passed through Kansas, I shortened my day and unfortunately picked a hotel that was way further off the road than I had thought. The upside of this is it passed a prairie research preserve, with a scenic lookoff. Here's a photo I took there the next morning, you can click it to enlarge it. They study the ecology of the prairie there and graze buffalo on sections of it. This lookoff is between the I-70 and Manhattan, Kansas, where I spent the night.
I really enjoyed the prairie between Kansas City and Denver. It was very interesting to see it morph from rolling hills to flatland, some of it farmland, some of it pasture, and some of it very, very unpopulated! It was a soothing day's drive, with no cities enroute (after the previous day's busy drive between St. Louis and Kansas City).