Hi, we recently returned from a trip to NZ.
I've got two boys 4 and 2.5 and had been dreading the flights. Our 4 yo is a real book worm and happy to sit for hours with books, so just took new books for him. But 2.5 yo is total opposite and never sits still for more than 5 mins.
We flew Virgin Atlantic and NZ Airlines. Both were fantastic. Very helpful and had packs for the kids - although the toys were a bit out of age range for ours, they just loved the idea that they had 'presents' from the crew.
I would also highly recommend the Klutz book with little cars/trucks, mentioned previously. I found this just before the trip and it was a godsend. Both my boys loved this book and it kept them quiet for ages.
I also took some small puzzle games eg. matching pair cards, etch-a-sketch, dinky cars, and sticker books, but actually had too much and didn't need to use them all.
The in flight entertainment on both airlines were excellent. Both had loads of animated films and TV shows eg. Hi5, Barney, etc. and computer games. The only thing was that the 2.5 yo wouldn't wear the headsets, but he was happy to watch without sound. Also, the call button for cabin crew is on the controller, so my two were constantly pressing for help by mistake. The crew were very patient though - must get used to it!
Meals were brought out quickly (or held back at times when they boys had fallen asleep and brought out later), but I also was a bit surprised by high sugar content of meals. I would intercept the meals and remove some of the sweet treats/drinks before the kids noticed.
We also whiled away the odd half an hour by wandering up and down the aisles and visiting the toilet, just to stretch their legs, which helped.
In general I would also mention that my two slept loads more than I thought they would and as a result didn't really suffer much from jet lag. We had a few disturbed nights of sleep from them, actually worse coming back, (which we did via San Francisco) than going out (via Tokyo). I'm not sure if this was to do with excitement of holiday versus being back home, or if direction of travel makes a diference. Anyway, dh and I found it much harder to recover than they did . . .
Hope the experience is as positive for you!