[Francis McClobber]

I’ve made the trip both ways several times. I’ve taken the norther route (80) the middle (40) and the southern (10).

Given that your trip is planned for the December timeframe, I would take the southern route. You can catch the 10 north of Escondido and then take the 20 to Dallas once you get into Texas. This route will keep you in the more moderate Southwest weather regions. From Dallas, you can start heading north on the 30 and pick up the 40 in Little Rock.

No matter what way you go, stop and see the country. It’s awesome!

[NonZeroSum]

You can catch the 10 north of Escondido and then take the 20 to Dallas once you get into Texas.

That's way out of the way from Escondido. It would make more sense to take 8 to Tucson, and pick it up there.