It would be about an 8-9 hour trip depending on layovers. Actually flying time I believe is roughly 6 hours. The time difference is 4 hours (so it would feel like 10 pm to us, when it's only 6 pm there). I do worry a bit about the time difference, since trying to stay at the park till 8 or 9, would be the equivalent of the children being up until 1 am. One night, sure... a few nights? Hello Spawns of Satan!
Yes, they would LOVE Carsland. They are HUGE Cars fans. Granted, they also love Toy Story, too, so will love that. But myself personally, I find Carsland more appealing.
We planned on doing Sea World as well. I'm not sure if we would still do that or not if we went to DL, as it's an hour away and we won't have a car.