Turlock California to Orlando FL in 12/21

Ditto of Paw Paw. If you are wanting to include the Keys; the time to make reservations there is now.

I'd say you can rely on the weather on I-40 that time of year. To be bad for at least one state.

I-10, boring and more boooooring.

East of Tucson, stop at Benson or Tombstone. Yeah, a tourist trap over a BS legend, but still, everyone's hear the legend.

El Paso - take the NM-404 exit to NM-213 to Loop 375 and miss El Paso.

Just after I-20 splits off, Balmorhea State Park is a wonder, or even better a bit south to Davis Mountains SP and the McDonald Observatory in Fort Davis. Also a neat place is Historic Fort Davis National Monument.

Big Bend NP is worth a week at least, but even a day driving through is worth the time.

Personally, I get off I-10 at Van Horn and take US-90 to San Antonio. Much less traffic and pressure. See how barren real western Texas really is.

San Antonio a couple days. Traveler's World RV is close to downtown and worth the cost I hear. Never been there, belong to TT and they have a park close, but you don't want to be there if you are not a member.

Try to cross Houston at mid-day and go straight through on I-10. Lanes are well marked. Check signs painted on the lanes, don't hunt for overhead lane markers.

Louisiana - well, mother's family is all Louisiana and I went to high school in the state. Good roads are not a thing they do well. I-20 is about as bad as I-10 as far as roughness.

Stop in Lafayette, or even Rayne. Get a sample of the real south, or a real nice place not too far off the interstate is Tickfaw State Park north of the big lake.

Do not try to follow I-10 through New Orleans. Baton Rouge - try for 10 to noon crossing the Mississippi River Bridge and remember you are looking for I-12 to cross north of Pontchartrain.

Just after entering Mississippi is the John Stennis Space Center. If you follow the space program, the Exit 2 Welcome Center is a must stop.

Mobile is no problem to cross and going through the tunnel under the ship channel, no issues for an RV. Nice park in the middle of the Bay.

Gulf Shores probably has the best beach on the entire Gulf and Atlantic coast in my opinion - and the crowds to match. But not too busy that time of year.

The Naval Aviation Museum at Pensacola is a wonderful stop. Might be biased. A plane that I flew on in the Navy is on display there.

I-10 Florida panhandle - Booring as Texas but with pine trees. Lot of broken pine trees after Hurricane in 2018. Night not all be picked up by now either.

Careful on I-75 from Lake City, especially near Gainesville. Been some horrible accidents along there.

One other warning. From San Antonio to Tallahassee - if the fog comes in and visibility gets low, try to get off the freeway and stop. If you cannot get off and stop, stay on shoulder and strapped in to your vehicle seats.
Same thing for windy area of I-10 and I-40 and dust storms across Arizona and New Mexico.

Take flash flood warnings serious. I saw water running across the west bound lanes of I-10 16 miles east of Deming NM (I was headed east) on Sep 9, 2020. Several vehicles including 18 wheelers pushed off the pavement by flood waters. Winds that day were so bad, I bailed out at Deming. Should have at Lordsburg.

If you take I-10, maybe spend a few days in Cajun Country -- the music and the food are amazing.

I went from Pamona to Orlando a while back. I-10 on the way.

I-10 is pretty boring, but at least you don't have to worry about the weather except for possible gulf storms.

I enjoy I-40 a lot more, but you can't rely on the weather.

We made that basic drive back in January 2015. We went from Jamul (outside of San Diego) to Seffner (outside of Tampa). We took I-10 the whole way.

Here's the route mapped out on Google Maps. I did it from memory and I think it's missing a Harvest Hosts stop outside of Tucson.

We didn't have any weather issues others than a couple of colder nights. Tucson was the coldest and we were poorly prepared for boondocking leading to a comedy of errors.