For most of our Disney trips we fly. We drove only once when flights to Orlando were cancelled for days due to Hurricane Charley. In that case we either drove or cancelled the trip - so we drove.
I don't mind driving trips but it is much easier hopping on a plane in Philadelphia and landing in Orlando less than 2 hours later.
For our May trip, we're planning to drive for several reasons. One is that I think the prices to fly right now are too high. I also don't like the extra bag charge most airlines charge. That limits what I can buy there and bring back. I remember I wanted to bring back a plant the last time I was in Disney during the Epcot International Flower and Garden Festival, but I decided it was too difficult because we were flying.
If we're driving, I can pretty much fill the trunk and the back seat (not that I would, but I can!). Since this trip is without our teenage daughters, it will be a quieter drive! And driving gives us the ability to explore some of the areas around Disney such as the Disney-created community of Celebration.
Gas prices are still pretty low and with a new car that has better fuel efficiency, the cost of driving currently outweighs the cost of flying. But if airlines prices plummet in the next couple of months and gas prices rise, I may be changing my plans.