Fred, perhaps it will be excused if I interrupt this thread briefly to tell you that we will be at Charolotteville at Misty Mountain RV Park, September 10, 11, and 12. We will be participating in the "Harvest Festival" at Monticello on Friday and Saturday. We stayed at Misty Mountain a couple of years ago for our first visit to Monticello.
And in regard to your question: we live just off I-20 in East Texas. Unless there is really bad weather you could follow I-20 all the way to where it joins I-10 as one possibility. Getting around Dallas/Fort Worth is not really difficult on I-20. It drops around south and when we have followed that route the traffic has moved along at freeway speed.
I think the biggest factor for your trip will be the weather. If it's not bad you could follow I-40 across New Mexico as you mentioned. Santa Fe is one of our favorite places to visit, but we have never gone in January.
We have made the trip to California following I-10, but we branched off at I-8 to go to the San Diego area.
Wish I could be of more help, and we are familiar with the routes all the way from Charolottesville to the West Coast, but all our experiences have been in the Summer.
