The Airtran situation was a crazy one - 2 parents, one 3 year old, they delayed the plane 15 minutes for her to get in her seat, she apparently kicked and hit her parents and was crawling under seats and they couldn't take off unless she was seated which they couldn't get her to do???
I have flown many times with all 3 of my kids and as a parent that travels with toddlers and babies I completely disagree with the parents and I am upset that Airtran apologized - for what? For parents that can't control 1 child?? Should everyone else be delayed or miss connections? Silly.
That said, we do prepare our children very well for the flights. We expect them to have good behavior on an every day basis so our kids know better than to hit or kick us anyhow. I think that is a huge part of it. We tell them, even though they are really little, that we are going on an airplane, that they must stay in their seats the entire time because we are in the air, that they must be quiet when asked and listen to the "pilots" - they can't distinguish pilots from stewardesses

. I also try to starve them for a bit before to make sure they are hungry and will eat/nurse as we takeoff(with special snacks I bring that are a treat) . We pack "surprise" dollar store bags for each of them - books, crayons, new toys, stickers, lollipops, etc. We talk to them alot instead of expecting them to entertain themselves - what are we going to do and when, where we are going, how cool the clouds are, etc. And if possible I hold off their naps so they sleep en route. We have flown to Europe, Florida, Mexico and Cuba (CDN here)and they have never given us a hard time, ever. I think if you share and enforce and reinforce your behavior expectations and you yourself set your example by not taking off your seatbelt at all during the flight - they won't either. My .02 cents.
Good Luck!