I think your idea for the air sick bags as treat sacks is hilarious! I love it! What are you going to fill them with?
It would be fun to fill them with some of the things you would get in an amenity pack, but more kid friendly:
a pencil w/ airplanes on it?
kid socks
pack of pretzels?
Plastic airplanes or maybe pilot wings?
Have fun. What a great party theme!