We flew to Australia with a 4 and 6 year old and it was just about manageable because the 4 year old could amuse herself colouring etc. We flew with Virgin, who were good and the flight was at night from UK to Hong Kong - the kids had a quick runaround at the airport for an hour and then back on the flight to Sydney - also at night. It meant that the children could sleep whenever they felt like it because the cabin lights were off most of the time. I do like the idea of a sky nanny though although not necessarily for the older kids.