We live way more than a 10 hour drive and thus fly every trip. I dream of living that close! We'd be there every long weekend with the allure of the mouse only one day's drive away!!! Different perspectives.
OP, how does it breakdown financially for you? Obviously doing the drive in one day would be cheapest. When you add in the cost for 2 nights hotel stay how much savings is there on driving vs flying? If the PP is right and flying saves you 6.5 hours, how much an hour are those hours costing you? That's how I personally decide flight times, sure 3 more hours in disney would be nice, but is 3 more hours worth $200? The answer is almost always no and we take the earlier flight.
It will probably cost us about $500 more for the whole trip to fly versus drive. Plus it will save us not only several hours on the way down, but even more importantly a lot less time coming home. If our kids were both older than 3 years old, driving is what we would do, but with a 6 month old in the car for 12+ hours each way in a car seat, I just don't think it is going to happen. Our oldest is much better in a car seat than our little guy.