M.P.
We only ever travel by car and have made that drive recently. Well...we went to Orlando, but pretty much the same. New Orleans we found to be out of the way unfortunately. We stopped twice because we made the travel part of our vacation. Shreveport LA actually has a really great science museum called Sci Port. If you are going to spend an overnight, that's a fun place....however it's still a bit too close to Texas. I prefer to do the bulk of the travelling the first day. Gulf Shores Alabama is pretty nice and somewhat along the way. Maybe you could splurge for a hotel room right on the beach for a night or something. Get up, walk the beach then get on your way?
Also, we always put together binders for each kid. In the binder is a zipper pouch for things like a new box of crayons, sharpened pencils, etc. Include a map of your route. Blank paper is fantastic for sparking imagination, and our favorite thing to do along the way is a scavenger hunt. ALL ages can play so your 13 year old and 2 year old will both have fun. Have the 13 yr old be in charge of making the list, but she has to include everyone's input. One of my daughters (5 at the time) wanted to see people picking up garbage. Another wanted to see 3 cows in a truck. See the fun? And we DID see that. We also added stuff along the way like...a bunch of onions on a bridge (they apparently fell out of a produce truck!) For the youngest, we challenged her to count how many bridges we went under.
Have a fantastic time. :)