You said that you'll take I-70 on your way back. I assume that means you'll be going through Colorado. Downshift or use your "Tow/Haul" mode while coming down out of the mountains; it's a 7 or 8% grade for several miles and is really hard on brakes. There is no good way to get avoid Denver, but avoid rush hour traffic at all costs. I-70 going East through Denver isn't as bad as I-25 anywhere going North and South along the front range.
Once you get East of Denver, I'd suggest taking highway 36 through Eastern Colorado and Kansas instead of I-70. It's a two lane road in Colorado and most of Kansas, but it get very little traffic and the scenery is a little better than I-70. Plus the hiway runs due east where I-70 dips south and then back north so you will probably same some miles. Once you're in Eastern Kansas the road by-passes all of the towns and turns into a limited access 4 lane road. It goes into Missouri just south of St. Joe and continues east through Hannibal so you miss Kansas City and St. Louis plus all the heavy MO I-70 traffic. Hiway 36 meets up with I-70 again at Indianapolis.
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