I'm definitely doing a me too here! But I'll include my rough packing list from traveling domestically with our two from birth on.
First, I agree with everyone who said pack, then double it! I bring the following on most trips (depending on whether you have connections, and how many, alter as appropriate):
Change of clothes - one for everyone, definitely two (or more!) for little ones.
Nightwear for the kids - something they can wear on the plane if their first three outfits get wrecked...don't laugh, it has happened!
Night-time diapers for anyone still in dipes, and even for dd who is out of them! I put them on under her undies when we fly. If she has to go "now, now, NOW" when we are taking off/landing/in turbulence, I am so out of luck! Better safe than sorry.
Snacks - goldfish, crackers, apples, granola bars, etc, as well as a VERY few seriously-sweet treat things (small packs of M&M's or whatever)
Ziploc bags - big and small, for breaking down snack packs into more manageable sized portions and for those unfortunate accidents that might happen!
Disposable sippy cups - SUPER IMPORTANT, won't fly without!!!! Nothing worse than a young 'un with an open cup on a *plane* that's bouncing!!! At least two per child, more if making connections. I try for at least one per flight.
DVD player/computer game/whatever entertains them
Kleenex, wipes (baby wipes and Clorox ones), hand sanitizer
Tylenol/Advil - for me. Just in case.
I am sure there are things I am forgetting, but these are the biggies I recall offhand. Good luck, and hopefully it will go great!!