Take a few things, but not too much, sometimes carrying it is more of a pita.
Pencils (pencil sharpener), sticker book and books are all great. The only thing we add to that is portable DVD player, snacks and i put kids music on my ipod. I bought some kids headphones and she loves it.

Something i always do is fill either a bottle or a sippy cup with a drink, so that they can suck on it on the way up and down. I also have a chuppachup in case of emergency. I don't regularly give my girls lollies, but on a plane i tend to give DD1 a chuppachup. She is so stoked to get and it and it takes so long to suck, it keeps her occupied, and it helps clear the ears with the sucking action.

2 hours will fly, by the time you take off they serve a snack it will be about time to descend again. Have a great holiday!