I would seriously think about NOT doing it. Not only will you have to deal with 2 long flights but also jetlag in two directions. We have 2 sons, 3 and 20 months, and would not dream of any flight over 3 hours for pleasure. Of course people will say "it can be done" and of course it CAN be done. If you have pressing business commitments of family overseas, children can travel anywhere. On the other hand, a holiday is meant to be pleasant, not a struggle. The question is whether you or your son will get anything positive from it or whether you will return more frazzled than when you left.
If you decide to do it anyway, sticker books are great, as are cuddlies to snuggle up to. Business class would be a real plus...but that depends on finances, and how many evil looks you are prepared to put up with! Personally, I would not take too many sweet snacks but maybe a container of fruit and some sandwiches to provide slow release energy. The fruit is also perfect for take off and landing. Did someone actually suggest ice to suck?! That sounds the craziest idea of all. A toddler can only hold ice in his mouth for a few seconds until it becomes painfully cold. Water dribbles out and then the whole thing comes out to melt on the carpet (or your bag under the seat) and does nothing to help the ears.
An Ipad is an idea but also stressful if it is dropped, dribbled on etc. Personally, we tend to manage without buggies as at least the children burn energy in the airport. They are going to be sitting down for hours as it is. In addition, I would have thought two adults could manage one child without reins or a harness?! It is when you have one adult and two toddlers that it becomes stressful and, even then, we have not resorted to reins (although it may come to it yet).
With all these recommendations to take with you, be careful to check baggage allowances as, on some airlines, they are quite limited and you may find yourself paying a fortune for overweight.