The point of my post above is my preference for serendipity.
I traveled a lot, more than 1M miles, and always enjoyed the seat mate. If they don’t speak, fine. If the seat is empty, fine. If they like to talk, fine.
My absolutely favorite was on a long 13 hour flight. I was in the aisle seat.
A woman about my age sat down next to me and gregariously introduced herself: “Hi! I’m Dee!” “Hi. I’m Lucky. After I finish this drink I will probably be sleeping for much of the flight so I can hit the ground running when we land. If you need to get up don’t be afraid to just wake me. I don’t want to suddenly wake up to find your crotch in my face as you are stepping over me.”
About an hour into the flight she lifted up the armrest between the seats, moved her pillow to mine and pulled the covers.over us. We slept really well. Nice.