I used to go out the with FAs routinely when I was at the regionals, even one on one. As far as "extra-curricular" activities, I am not attracted to 95% of the FAs out there to begin with, so the handful of instances I've ended up alone with an attractive FA are pretty few and far between.

I am more careful now that I'm at a major, but we only stay with the FAs on international long stay overnights. I'll still go out sometimes depending on the crew, but I usually end up ditching them at some point to go do my own thing. I've only had one instance where I went out one on one with an FA and it wasn't even planned. We got to the hotel late, I told the whole crew what I was doing and invited whoever along, one younger cute FA showed up, and off we went.