I have Circles set up for groups of work colleagues, professional contacts, family, and friends who I like to share fart jokes with. In each case, I can interact with those people in a manner appropriate to the nature of my relationship with them. That solves the Facebook problem for me (I didn't use it because I nearly never had anything I wanted to share with everyone I knew in the world), and also creates an environment where I can have fun with my friends and be professional with my colleagues without compromising either group.
I really like it.