S.O.
All the apps from Duck Duck Moose are great and very interactive (specifically I have Old Mac, Wheels on the Bus, and Itsy Bitsy). My son is 20 months and he can play with them all. I also downloaded a virtual fish tank where you can feed the fish and knock and the glass and such. It's pretty fun. A game called Peekaboo Barn is really fun. It has about 10 or 12 animals, there is a free version you could check out and then buy it if you like it.
There's so many kids apps you can download for free. I also purchased some Sesame Street episodes (through iTunes) and put them on my phone to watch.
Good luck with the flight!