International F & J due to the large amount of space from one seat to the next, rather rarely..
Domestic F, well that's a different story! I like meeting new people onboard planes. They always have fascinating stories and of course from my end I always mention FT and MP..
2 weeks ago, my seatmate is the wife of a retired United Mechanic. The husband was on the other side of the aisle. We had some lovely conversation too!