C.S.
I will just offer a small bit of advice that I read and used when I took my daughter on her first plane ride (she was just under a year). Bring one or two new things and don't let your son see it until you are on the plane. Just a new little toy of some sort- new things always hold their attention longer than old ones. Also, bring things out of your bag one at a time. Start with a sippy cup in the begining to help with the ears and just talk about what is out the window and the people on the plane. Resist the urge to start taking out toys and handing them to him right of off the bat.Only when he starts to show signs of bordom-take out one toy- not the new one yet, then once again wait for signs of bordom and move on to a snack and so on. Try to bring some sort of new snack he hasn't tried before too. Also, never underestimate the power of ordinary items. If your son is like most kids he would love to have something from your purse that he doesn't think he's supposed to have- not something dangerous- just an ordinary object- a mirror, an old receipt, your sunglasses- you'd be amazed how long they will play with something like this. If you have an i-pod that you can download videos too, you can download cartoons to it. I did this rather than bring a portable DVD player because when you are traveling with a little one the last thing you need is another bag.
Good luck- also, prepare yourself for the rude people and just know that you will probably never have to see them again.