We used to fly southwest, but we ended up moving closer to Disney it takes 11-13 hours to get there, but I actually think that the anticipation is really fun (we also get ice cream or something which is a big highlight since we've been sitting forever...The only bad thing about driving is that it is always so depressing on the way back!
Our next trip, we are flying from MI. After that our DD5 and DD2 will be old enough to tolerate the 24 hour car ride. We have family in Tampa so having a car is a bonus.