I am friendly with my staff, but not friends with them. Some come to me with their personal issues if they think I can help, and I do where I can, but otherwise, I maintain a safe distance.
Interestingly during her performance review, one of my girls recently told me she views me as a boss and as 'like a big brother'...this was nice.
Also interesting, one of my staff, and one of our regular suppliers, came to my birthday party last year. As polyrock800 from SF (who was also there) can report, that night was a little reckless. 300 odd people, and me on amphetamines running around in camo gear with a vodka laden squirt gun.
The surprised feedback..."my boss is reeeeeally fuuuun!" - a good indication that generally I keep the game face on at work, and keep the lines between work and play pretty clear.
One of my mates runs an ad agency here, and basically his best friends are his staff. I think this is all fucked up. Those boys are out hammered until 5 am like six nights a week, stumble home, sleep 2 hours, and go to work. Do a fuckload of pills together, go whoring, whatever.
I just don't want my subordinates seeing me in that light (I am not that bad anyhow, I go out a lot, but weeknights I am generally in before midnight, 2 at the latest), and similarly, I don't want my subordinates showing up three-hours-post-tequila and facing my clients.
That said, he seems to make it work, so who am I to judge, but still....