I understand that people from the East may not realize how big the West really is. It's possible to drive 12 hours from Denver and still be in the state of Colorado. (not all interstate, of course.) So, if you want to have time at the end of the day to relax, I wouldn't go over 600 miles a day MAX, and figure fewer per day if you drive I-70 through Colorado. The shortest route is I-70 through KC, Denver, I-15 through Las Vegas.
I-40 is more heavily traveled cross country because it's easier and much lower elevation over the Continental Divide. If you want to go through Dallas, you're better off Taking I-20 to I-10 and going across the desert southwest. In this case you'd want to go Columbus, OH to St. Louis, Tulsa, OK on I-44.
My advice is to spend the night in Columbus, Ohio and make a decision if you want to stay on I-70 or go south based on the weather. Someone predicted that due to El Nino, there may not be much snow this winter in Colorado, but more in New Mexico.