I'll be doing the same thing December 21 to January 5th. Right now my plan is to slab it between Orlando and Tucson on I-10, then see how the weather holds for the Tucson/Los Angeles leg of the trip. Ideally, I'd like to go into LA the southern route via back routes near I-8, then loop back through Joshua Tree National Park via I-10 on the return leg. December 29th to January 3rd will be 5 days of fun riding between Los Angeles & and Austin.
Eastbound from Austin... weather will be much less of an issue. We just don't get snow, but might get cold snaps. Other than rain or unexpected deer, your biggest worry from Houston eastward would probably be the possibility of thick fog. Since I need to be back at work on January 7th (and have ridden several times between FL/Louisiana) I plan to just slab it during Jan 4-6 from Austin to Orlando on I-10.