When my daughter was small I used to make 'airplane bags'for her use on the plane. We would shop to pick out things that were cheap, fun, and unusual (wiki stix, small hand held game where you put the ball through the pinball machine by manuevering the game up and down, small fun coloring book with tiny pack of crayons, etc) all 'dollar store items. We'd put them in a paper bag and the day of flight as soon as we were airborne she got to open the bag and begin to play with those airplane goodies. We also make a big deal out of shopping for chewy 'airplane candy' and she got to chew that just as soon as we were taxi-ing down the runway. (this was to keep her ears open so no in-flight ear pain). I also gave her a tiny dose of Benadryl to dry up any fluid that might be in the ears so it wouldn't be forced into her eardrums upon take-off. (this was recommended by our pediatrician) we did it each time we flew and never had ear trouble of any kind.
My daughter is 18 now and still remembers her airplane candy and her airplane bags full of goodies.
Another great thing is to buy a 'Viewfinder' for the first trip with just one set of slides, and on each subsequent trip, buy a new set of slides to be viewed on the trip. I know it sounds old-fashioned, but years from now technology is going to change and a dvd and player probably won't be able to be used, but a viewfinder - well, even 20 years later you can still click it and look back upon all those shows and movies that you enjoyed as a child. Great fun! K. d.