We have driven down a number of times as well as having flown and rented a car.
When driving down, we always left immediately after the kids got out of school, meaning a short work day for us. Timing is everything. By doing this, the kids ate supper on the way down while watching movies in the back. While stopping for fuel, we let them change and get comfortable for another movie as they fell asleep. By the time they'd wake up, we'd be in Daytona. We'd then stop and let them change, use a restroom, get breakfast and finish the final 45 minutes (or less depending on traffic) to Orlando/Kissimmee. You don't know how nice it is not hearing "are we there yet?" every few minutes since they are sleeping and waking up already there.
Having said that, we're doing something a bit different this next time. We're having the grandparents along at FW (they're driving down early to visit some family and other friends before getting to FW and meeting me there in time for check-in). I'll be leaving sometime after them towing the trailer down, minus the wife and kids. Instead, they are flying into Orlando and taking the Disney shuttle bus from the airport to WL were we'll meet them at. They get in three hours after we check in and get the site all set up. So we, in-laws and myself, can relax for a litle bit or take in the Fort before meeting them and going out to Bass Pro Shops for some shopping (OK, we ALL are into fishing BIG TIME) and dinner. I'll have everything, so they can just wisk right out the airport and not have to wait for any luggage. They'll drive back home with me.
That should give you someting else to consider as well. It's less than 3 hours flight time and they like flying. I on the other hand, well, I hate flying, so I am all set driving. By the time we leave and head for home we can either stop for a meal to break up the driving and then continue straight through and they can wake up as we pull into the driveway or we can stop somewhere along the way home and spend the night, taking our time coming home.