D.M.
I found this site when I started traveling with my son who was only 8 months old at the time...now two years old.
My biggest thing is I make a checklist of ALL the things I need...really my prep begins two weeks before I'm due to go anywhere, by plane or car.
Airlines make HUGE exceptions for packing carry-ons when you are traveling with infants. Check and print the updated guidelines for your travel dates. I always pack everything I would normally carry in a purse into a backpack, and then have my carry-on with tons of baby supplies. Depending on the length of your flight, pack accordingly for food, snacks and then extra just in case.
Pack checked luggage with foods you KNOW you won't be able to find when at your destination, and don't forget favorite items like lovies or blankies.
For on the plane I have books, stuffed animals, puzzles, crayons, coloring books, portable DVD player, travel games, flashcards...stuff that you can pop in and out of a bag.
Try your hardest to stick to your normal routine, and don't deviate. It may be hard when you're all so exhausted, but the transition from travel to home will be easier if you do.
It's really a learning process and I always forget at least one thing!
http://www.flyingrugrats.com/index.htm