ditto to what disboo said!
Think about the amount of time you actually spend flying.......from leaving your front door to arriving at WDW!!
For us from OH....We left our house at 2:30 and arrived at CBR at close to 9pm. So that is about 6 1/2 compared to a possible 18 hour drive. So for us....we fly.
But.......what if the flight is delayed, etc. Once it took almost 13 hours for us to get home.....cancelled flight, etc, etc,...
Also add in the cost of the rental car if you get one for the week, or the cost of taxi service to WDW from the airport.
IMHO if the drive is less that 10 hours, I would drive to save the money!