Another vote for a dvd player. Also, the Leapster games, and a mp3 player. Also keep in mind the current restrictions on what you cant bring on board.
I dont know how long your flight is, but we always made our son walk through the airport (and used the stroller as a luggage cart for our carry-on) unless we had a tight connection. It wore him out and he ended up napping on the plane. While waiting to board the plane, we walked him around some more, and he loved watching all the activity of prepping the planes for flight.
alison