K.C.
My sister in law lived in Oregon, USA and traveled frequently with her daughter to see Family in Germany, and she offered me great advice for flying with young toddlers. She would make a trip to the dollar store and buy up a bunch of cheap toys, stickers, etc. and also a trip to the grocery store for "special" treats that she normally didn't give her daughter (including suckers for example which last a while. Then she took all of these items and wrapped each one individually like a gift, filling a carry on with them.
Start talking to your daughter days before the flight about what to expect and make it fun, read a book about airplanes and maybe get an airplane toy. On the flight do as much stalling as you can but when needed, give her a toy "gift" and once she has played with it for about a half hour and is getting bored let her have a snack "gift" and so on and so forth.
Also, consider bringing an iPod with music she enjoys and short childrens videos on it as well or a portable dvd player. Good luck.