J.P.
Soooo many things. Her temperament is really only known to you, so most of this will be a judgment call. First, for stuff - get something like a peapod from onestepahead.com. It is much easier to travel with than a playpen. Is she getting her own seat? If so, get the wheels and handle to transport it through the airport. I would bring a few things for her, but if needed, you can always go to the store rather than bringing the store with you. My son's favorite thing at this age was the plastic drink cups and ripping up the magazines. Also, he mainly drank LOTS of milk. You may want a little "bribe bag" with some things that she hasn't seen before. A new baby doll, hotwheel, etc.
If you schedule it during a nap, that may help too, and if you are relaxed, so will she. to make yourself feel better, go to walmart and get one of those jars of earplugs. You can pass them out as needed. Let her run in the airport. You may get dirty looks, but they will be much happier with her running up and down the airport than screaming on the plane.
Also, tell her what is going to happen, and what you need to do. As far as the time change, how long are you going to be there, and what is her schedule like? Is keeping her on your schedule going to make it impossible on you?