In general I would agree with the advice of do the TATL first and to avoid JFK especially if you do not fly a lot and have children. The only two things that would change that is if one had better seats open on the TATL or if the total travel time was significantly different I would go with the shorter time. One final thought with the cruise, if you are booking airfare separate from the cruise line, I would make sure you are arriving a day or two before the cruise leaves and coming back a day or two after, delays going to Europe can be a full 24hrs especially in the summer and if you need enough seats for the whole family. You wouldnt want to miss the cruise because of a delay. Good luck and enjoy the trip.