Well, this only works if both of you don't mind driving overnight.
We come from NY so our drive is about 19-20 hours of driving time. We used to split it up but that means two days of driving 10 hours each. Our three kids work on each other's nerves by that time, needless to say mine.
So the last two times to Disney (and a week from today...yaaa!!) we have done the overnight haul.
We start out at 6pm and I have something packed for dinner. Sandwiches, usually. About 10 or 11pm, the kids start nodding off to sleep (kids are 14, 11 and 7) and sometimes I get a little nap then too. DH drives until anywhere from 2-4am, then I drive a couple hours. The last time, both of us got sleepy around 4am so we pulled into a lighted rest area and slept for about 1 1/2 hours. Then he usually drives until breakfast time, 8am and we all have a good breakfast somewhere around the Florida state line.
After breakfast, DH gets about 3 hours sleep..........the kids are awake now and busying themselves with games or DVD's or music. Then DH and I switch and I get a little more sleep too.
We ususally pull in to Orlando about 2pm. We get to the hotel and swim and relax. Off to bed early that night to get a full nights sleep and hit the parks early the next morning.
This way, the kids only have 10 hours wake time instead of 19-20. We find we are all much nicer to each other this way.
Ofcourse, we will be in Orlando for 15 nights, so maybe this wouldn't work with a shorter trip.