Some things to add
- Have the child get used to and use headphones as a norm. Watching parents struggle with iDevices and headphones for the first time on a plane is too late
- Have them get used to using the iDevices with no sound. Children can spend house just watching visual stimuli - it's fine, it is useful for when the headphones fall off or get annoying that they are no always expecting sound - you don't want to be in that situation where the child demands sound
- The extra seat is a necessity. A two year old takes space, wants to explore, it is not the time to nickel and dime - you also benefit from extra luggage, their own meal, the space of a seat etc etc.
- Children will make noise, sleep at the wrong times, get stroppy, they just have not year learnt to keep it all inside. Parents who try have sympathy and help, parents who look like they are disowning their kids get no sympathy.
- Share the parenting. Flights take time and are exhausting, having you both "on" will end in tears, take a rest, even if that person knows they get to watch a film without needing to worry
- Take twice as much of everything. Children will have accidents, spills and the like. Also it is often hard to judge temperatures.
- Take extra tops for you and your partner. Children will have accidents, touch things, spill and you are next to them
- take lots of wipes - children touch things - and people who should know better put feet on tables, leave stuff around, empty plates etc
- airports are great places for walking - tires the child out ;-)
- invest in a very good harness system to have the child on your front (or back) - prams are no always available and kids sleep and sometimes you just need to move
- direct flights - and think of airlines that are good with kids (e.g. CX, BA, QF, NZ) which may not always be the best.
- get a sky flyers log book - airlines other than BA will happily add their flights
- sign up to FF programs - every flight is a step towards lifetime status - ours had QF Gold by the time they were 18 years
- carry all your own food and liquids - or buy extra at the airport - delays happen, food does not get loaded, be self sufficient - throwing food out is better than a hungry child (or parents)
- if you get an upgrade, give it to your partner!
- ignore anyone with annoying opinions on what you do, although listen to people who look like they have done it before, accept help from people (within reason).
- bring books, a cuddle and a book being read is very soothing and familiar - some people will be annoyed, so what. (children love familiarity, planes and airports is not the place to try new things)
- brings lollies of something to suck on landing and taking off, the eustachian tube is not fully developed in children so ears do not pressurise as well.
- emergency cards - for some reason, children love these and will play with them for hours
- wipe down all surfaces - children touch, suck and lick things
- bring familiarity - blankets, toys, cuddlie things
- never have a favourite cuddle toy, buy like 10 of them - then when one is lost, it is not a drama, he/she was just hiding in a bag
- make a medical kit - if a doctor offers a script, always fill it and put it in a medical kit - while not advocating self doctoring having a supply and reasonable care can get you from A to B and then to a medical centre if required
- have good travel insurance, and do not be afraid to use it
- have both of you check the seats and overheads - you will be very tired, things get lost, get into a routine of double checking.

And enjoy, airplanes are not the place to try new things, focus on familiar, also be flexible, it is not a life-long nutritional disaster if the child has two icecreams!

And congrats btw. :-)

KF