My tip would be to invite another family with children of a similar age to go on holiday with you! My Wife and I prior to having children always enjoyed travelling with one another only - but with two children now - we have fantastic holidays with another family! Of course, you have to choose correctly and know that the children will all get on! Look out for the hotels with good kids club (they'll enjoy them when they are with their friends). A great plus is you get chance to have an evening as a couple, when you can take it in turns to baby sit for each other. On the plane - sticker books, crayons etc etc!