Departures this time of year very generally favor a departure from runway 31L/R, which favors sitting on the right side, as there is a sharp left turn after departure that gives a great view of Manhattan from the right side of the plane. I'd give that a > 2/3 chance of working.
You could improve the odds by taking a crash course in reading aviation weather forecasts and changing your seat based on that but it's really not worth the effort.
Thanks for your fast reply. Should have made it clear that I'm only flying in September. But since all seats are open, I can't decide which side to pick. Decisions decisions....
Cindy