We've travelled several times between Australia and Montreal (over 24hrs all up) with 2 boys from the time one they were 6 months old. My advice is be flexible. Either way one of you will be tired and the other(s) wound up. Your life will be made easier if you recognize it'll be tough but make the best of it . Let them run off copped up energy away from the hustle and bustle of a busy airport. Outside the terminal or in un-crowded airport areas. Kids are kids. Life is too short