Is there much time difference in the two routes? Very little according to randmcnally.com Also, if anyone would know, which route, for the most part, has the "cheapest" motels available? Thanks!!
What kind of vehicle are you driving?
The route along I-40 is a more gradual elevation change. I-70 crosses the Continental Divide via the Rockies. If your car does not handle mountains well, it will be a slower trip. Plus there are several construction delays near Vail.
"Cheap" is something I avoid at all costs. But I would guess you can find more economy-priced lodging along I-40 than I-70