East coast of Colorado to Grand Junction on 70 W

If you do not want or need to go through Denver drop south to highway US 50 to cross Colorado.

The grades are not much different and the traffic is less especially truck traffic on US 50.

US 50 is in very good condition (much better than most Interstates) and there is passing lanes on most of the road.

Or go North and cross Wyoming. Depends on your final destination and what you want to see on the way.