The only thing I found that entertained either of my boys when we flew was books - and LOTS of them !! Lift the flap books are especially popular with the 1 to 2s - just be prepared to be repeating yourself and still plastering that 'amazed
' look on face when you see the cat under the basket again.. and again... and again..
Either that, or a portable DVD player! I really couldn't get them to engage with much at all toy wise - they are too boisterous to be given puzzles really.
The other thing I found to keep them sitting still was food. I took hundred of snacks!! Fresh fruit like grapes/blueberries, sandwiches, cow & gate biscuits etc.
You older boys might appreciate a colouring book or two for the flight, maybe even an activity book or one with stickers.
I have taken them abroad at 10 weeks, 13 months, then when Benji came along- 8 months & 2 years, and again this summer at 23 months and & 3 years - LOL we must be mad..!
I find singing songs (much to the annoyance of other passengers) and clapping games work too. It's really just about keeping their mind off jumping about!
I wish you the best of luck with the travelling