H.R.
We travel all year long. I try to keep the flights as fun as possible. I bring several DVD's and recently began bringing Books on CD's that that are interactive, the child can listen to the story and when they hear the bell they know to change the pages. My three year old never hits the mark but LOVES the play of it. There are also large old school head phones that work best for their little heads. I bring a couple favorite small toys and books and also wrap up new surprise items, a new book or two or small something I can wrap in pretty paper for them to open. A little car or puzzle, no matter, it's just in case they hit the wall. I bring loads of snax, all liquids can be asked for on board but bring a sippy cup, it is soooo much easier. I nursed still at that age which was heaven! All the kids were instantly calmer while I could still nurse them. I think once I stopped planning our flight and began planning to be prepared it all fell into place. All kids are different. I do always try to keep them asleep for as long as possible, even on our flight to Australia, twice a year, every flight is different for each of our kids. Just relax and go with the flow!
Good Luck!