I would definitely contact the hotel to confirm your reservations (same thing with vehicle if you're renting), make sure you have made whatever plans to store mail, also begin some of your packing (if you haven't started), make care arrangements for any pets.
Also, be sure you have all of your money, along with (credit cards or travelers checks if you are taking them) in order. Before leaving out for the airport, definitely make sure to double check if you have your keys and airline tickets, might want to check the status of your flight the night before.
As far as occupying plane time: how about bringing along a favorite book you haven't read in a long time, a WDW guidebook to read over again, and some current issues of any well-liked magazines.
As far as bringing along trip items: rain ponchos, snacks if you don't want to buy all of them once you arrive, cell phone if you have one, and paper form hotel/car reservations, swim suit if needed, comfortable walking shoes, hat, sunglasses, sunscreen, hairdryer, and misty fans if desired.
Hope this helps (and I didn't leave out anything very important); also if you have a packing list go over it twice to make sure you don't forget anything.