Oh, thanks. That is the longest stretch of "nothing". Limon is like approaching NYC!!

The places near I-70 in Kansas which are most likely to appeal to your boys are (in order):

Natural History Museum at the Univresity of Kansas in Lawrence
Kansas Museum of History and the Capitol Building in Topeka
The museums on Fort Riley include the Custer House, U. S. Cavalry Museum and others.
Rolling Hills Wildlife Adventure Zoo west of Salina
Sternberg Museum of Natural History in Hay (this might be the best bet)

If you are willing to drive a little farther, the options really go up. For something unique, drive up to Lucas, the Grassroots Arts Capital of Kansas. It would be a great place to spend 2 or 3 hours. http://www.kansastravel.org/lucaskansas.htm

Or run up To Manhattan with the great medium sized Sunset Zoo and the bug zoo at KSU. While on the Kansas State campus, visit the Call Hall Dairy Bar which sells ice creams and cheeses made on campus.

I suggest (as others already have)the Sternberg Museum in Hays and the Rolling Hills Wildlife Zoo near Salina. My kids loved both when they were that age.

Thanks all! We did stay over in Kansas City. We are staying in hotels, as it was too cold for a while to camp. We are heading out around 9:30 to drive toward Colorado. We'll stop at once of these places I'm sure!

Please let us know how it goes!

Safe travels!