I also suffer from insomnia and never sleep on flights, but still manage to go for shopping weekends in NYC without too much trouble. I suggest getting as much sleep as possible before the flight, then doing something taxing for the first few hours of the flight (like puzzles etc) so that for the second half of the journey she's mentally tired (which will make her more inclined to sleep) and if she can't sleep then to try and doze (basically lie back, shut your eyes and think of nothing while still awake), as this serves the same function as sleep in the short-term and will enable her to keep going when you arrive. All sleep is is a chance for your mind and body to rest and recharge, which you can do while still technically awake (for a short-term period). Plus the rule of thumb is that you never get jet-lag on the way out, so none of you should be too tired anyway. Have fun!