In our experience the front of the plane and the back of the plane usually get to Cancun at just about the exact same time. I know it's nice to sit next to your friends or significant other but since you probably regularly spend hours at a time apart from each other at work etc don't let something like being placed in non-adjacent seats really mess up your trip or stress you out.
We love talking about our boundaries and desires on the flight down. No fun doing that with a stranger
I hope one of these flights we land next to you on the way down. We layover in PA often and that would be a much more interesting conversation to overhear than the normal ones I have gotten stuck listening to on the plane. I completely agree that it is always more fun sitting next to your travel companions on the plane but I would hate someone to stress out over a few hours apart when their trip is days, weeks, or months in advance. On a side note, my sister always purposefully books herself apart from her husband because he has broad shoulders and she would rather gamble that she may get a smaller companion. She also likes to be able to nap on the flight without feeling guilty that her husband would rather talk.
