If you have kids, buy a portable DVD player before the first time you fly with them. The players cost only about $75, and trust us, it's a worthwhile purchase even if you use it on just one trip. (Make sure the battery lasts at least two hours — and that it's charged beforehand.) We would also advise picking the cheapest unit possible, since your kid probably doesn't care much about screen size or whether the player can handle digital files and will probably just scratch the screen and squish food into the crevices.