I have lots of time under my belt in J with little ones. My experience is that they find it a lot easier than we do ! I often have the centre seats on the lower deck - row 14/15 ? I have used the bassinet positions on the bulkhead, but found it more of a pain as whenever the seat belt signs went on (which was a lot!) we had to remove Sam from the bassinet to my lap. Make sure you have the favourite drink/food and tire them out! A good toddle round in the dep lounge to stretch legs before a long flt works wonders! I have never been chkd into upper deck when travelling with kids, I think they try to keep it a bit quieter up there...also, if they are not sleepy then we used to go for a walk down to the rear loos and back up the other side. A favourite toy helps too...good luck, and don't worry..get them used to it early and you'll have no problems when they're older...my two are old hands at long haul now...Ellie often helps pour drinks in the galley if the crew is friendly !The crew really appreciate well behaved children....