I've driven from NC to FL 2-3 times per year. Unless there is construction or an accident, it isn't bad. Here are my tips:
Savannah is a good place to stop. If you stay at the exit near the airport there are tons of hotels.
The worse place to drive is between DC and Richmond. It is just one big long parking lot. You can't really avoid that though unless you go way out of your way. I have a GPS and whenever I hit a slowdown I pull off and find drive on parallel local roads for a couple miles, then head back to 95 and get back on if the traffic isn't stop and go.
Also, SC and GA are both notorious speed traps and if you have a cruise control just try and go the speed limit.
Jax can be congested - there are ways to get around if you get there at a bad time. I don't do 295 - if your driving south there is a new road with a big bridge to the east of downtown that is a good alternative. For a while you have to drive on a non-highway, but if downtown traffic is congested it is a good alternative.
Finally, if you are going to Orlando first (as opposed to Canaveral) when you get to Orlando, if it is anywhere close to rush hour, get on the Expressway right near Sanford, and take it all the way over to Disney. It will cost you money it tolls, it is more miles, but it is the same time if it isn't rush hour and saves you money if it is. My GPS never wants me to go this way, but I am from Orlando originally and you don't want to be on I-4 during rush hour. You should also get an E-pass transponder so you can breeze right through the tolls. I believe you can order them online, or pick them up at a Publix.
I've heard bad things about trying to do I-95 all the way down from Virginia to FL. Is there a better route? If not how much time should I allow? We are thinking about staying in Savannah for one night to break up the trip. Any advice?
Oh, we are going down on the Saturday before Thanksgiving so I'm sure that will add traffic.