We purchased a number of new things that DS hadn't seen before....only cheap little toys and books.....we then pulled one out of the bag whenever we thought he was getting a bit board.....this worked well for us.
I'm hoping he will sleep, but he can sometimes be naughty when it comes to nap time. If he gets to find out he can walk down the aisle it will tantrums at Dawn
I thought that if they were under 2 and you bought them a seat that they had to have an FSA approved seat brought onto the plane by yourselves - this may be just the US airlines because that was what we would have had to do on Continental!
What about a portable DVD player? Best present my DD ever got. She got it for her 2nd birthday and it keeps her quiet for hours when we are going on a long journey.