Home from work and the gym and have a little more time:

If you like history, and you are travelling through the Kansas City area you might enjoy the National World War One Museum, the only museum in the country dedicated to that war, http://www.theworldwar.org/s/110/new/index_community.aspx

Also interesting in the area is the Truman Library and Museum, and the Truman home in Independence, MO.

http://www.trumanlibrary.org/  and  http://www.visitindependence.com/  for many interesting sites in Independence.

Another nice stop in central Missouri (3 miles off I-70) is the town of Rocheport, not for history, but for the Missouri river. A trailhead for the KATY trail there makes a great place to get out and stretch with a little walk along the river on the trail. Bike rentals are also available at a shop by the trail. There is a great (moderately expensive) restaurant and winery overlooking the river just at the edge of town called Les Bourgouis. They have a store on the highway that sells their wine, but go on to town for the restaurant.  http://www.missouriwine.com/Blufftop-Bistro.php

A couple of things that might be missed in driving through the western half of Colorado: Glenwood Springs has a vintage sulfur spring and pool, several good restaurants, and a great biking trail (16 miles) along the Colorado River by the interstate. I have rented mountain bikes there and done that. You would think that the interstate being so close would be noisy, but it is hardly noticed, and the sounds from the river cover the traffic quite nicely. Next, the Colorado National Monument by Grand Junction is quite beautiful, and well worth the drive around it. Enter on the east side of town, and you will come out on the west and be on your way again.

On and on . . . it seems there is something beautiful and/or interesting everywhere I go, along with wonderful, helpful people. Sounds like a great trip and I know you will enjoy Utah, and your trip home also.