Answer:
Check your airlines policy for things like booking bassinets for long haul flights - if you need one you will need to book it in advance. Likewise, if you want to take a carseat on board, it will probably need prior approval.
Also, check what food will be available and at what times. You might want to consider taking your own so that you can feed your children in your own time. For toddlers, snacks such as a little bowl of cheerios (without milk) take up plenty of time in the flight.
For entertainment, pack some new toys if you can, stickers are great even for young toddlers. Always opt for silent toys! For young children, if you have one, a DVD played on a laptop with headphones and with enough battery power is good entertainment for an hour or two.
Some medics advise that sucking doesn't actually make a difference to babies ears hurting, but many parents would probably disagree. If you can get a baby to take milk during take off, it at the very least will distract from the noise.
Even though the baby change facilities are usually near the back, apparently there is less turbulence at the front - so it is best to sit there.
There are so many things to suggest -