We treat it like a car trip; make sure the kids have lots of things to keep them amused (toys, books, etc; we have a backpack we call the "bag of tricks" specifically for traveling and restaurants)
Depending on the age of your children, bring along a bottle, pacifier, chewy fruit snacks and/or gum so they can "pop" their ears a little less painlessly; make sure, however, that you don't dole out all the treats until you're making that final run up the runway to take off, or you may run out too soon!
INSIST on a potty break (or diaper change!) before boarding!
And relax; if you're calm and treat it like a huge game, your kids will be, too. If you're stressed....they'll be the screaming kids everyone tells their families about.
Have a great trip!