I've done the drive once from BWI area - it was fine (and fun!) going down. My kids were 2 and 4, so we left from their preschool at noon, picked up DH, then got on the road. We were going to stop for the night, but at 8pm, they were both sound asleep (they were usually asleep by 7pm) so we kept driving..... and driving..... then pulled into Orlando at 1:30am. It was fine, but I was exhausted the next day (and they were up at 6am!).
The drive home was not fun.
We only did this, as it was right after 9/11.
Have you considered looking into airfare from BWI? We usually get good airfare with SW or Airtran.
Otherwise, make the best. Look at it as an adventure. You can take all your stuff (we had the back of the minivan filled to the brim, as we were gone for 2 weeks and had a condo so had non-perishables, case of water, case of juiceboxes, double stroller, etc... also things like laundry soap). I used platic storage bins in lieu of luggage for these items. Then we did have one overnight bag packed - good thing as we arrived in town earlier than expected so got a room nearby the BWV for the night.
It is a long drive, so I honestly would look into any airport within a few hours' drive. Coming home, you may thank yourself.