"I would second the motion to avoid I-80 as much as possible, especially east of Des Moines, Iowa".
We live south of Grand Rapids Mi. and spent a Month in Co. and Utah last year. On the way back we went I 70 to 470 around Denver and picked up US 36 just East of Denver. HWY 36 was awesome, cruise set at 65 with no traffic all the way to Hannibal MO., then I-72 in Hannibal, north on I-57 to Hwy 24 in Gilman IN. Once on Hwy 24 you can take Hwy 421 or Hwy 31 north to I-94. It might take a little longer this way......but all it takes is a traffic jam in Chicago to make it up. Hwy 36 is a great way to avoid St. Louis and Kansas City and some of it is a limited access Hwy.
We travel to Ryan Park WY. from West Michigan a couple times a year. We are unable to avoid Chicago, so we travel through Chicago between 11 pm-4 am Central time or Sunday early morning.
Bob