We went to Australia last Nov with our 9-10 month old. We took night flights where possible so that he would sleep. We flew with Singapore Airlines - who were fantastic with children.
You can buy Medised or Calpol night which has a mild antihistimine in it that helps them sleep. Just changed rules for selling it for under 2yrs - but this is only as some parents are overdosing babes with it as it also has paracetamol in it. Most of my friends have used this for long haul flights to help settle them if they get fractous.
We took disposable bibs so that we didn't end up with lots of washing and so we could throw them away. We took travel packs of baby wipes (from asda or waitrose) as they are smaller but just the right size for hand luggage. Used the 3 clear washbags from M&S to put things in - bottles and beakers etc in largest one, nappies in middle one, cosmetics and drugs like calpol sachets in the small one.
best advice we were given was to pack small toys that you don't mind losing (e.g. cardboard books) and keep them for different parts of the journey so they get a treat. (Also means you don't worry if you lose them on the plane). Ask friends for old toys, go to poundstretcher type shops etc - don't have to cost much but things like plastic little people, toy cars.
Travel snacks we found easy were - rice cakes, mini boxes of raisins, organix soft rusks mini packets, mini cheddars, breadsticks. Grapes, kiwi fruit, bananas, apples were good too.