I've been a big fan of the "try something new for 30 days" idea for some time now. My big project for November? Not using Facebook. (Also NaNoWriMo, but that… is not as successful so far.)
I signed out of Facebook completely November 1st and haven't signed back in. Deleted the Facebook apps from my phone and tablets, and removed the bookmark for "most recent" (lies! damned lies!) and the tab in Chrome. Habits die hard.
My time on Twitter is up, predictably, but not enough to offset the time I don't spend on Facebook. Also have dipped a toe into Google+ a few times, but the network there is much different, and I don't have as many close friends that really use Google+ that frequently.
Net result so far? Positive. Will I start using Facebook again in December? Probably – it's still the most effective way to keep in touch with some friends who don't do email, don't blog, aren't on Twitter, etc. It's also still really useful for organizing events. (Though I've found that people don't always closely read for details in the invites…)
More than likely, though, I'll limit my Facebook consumption to once or twice a day, instead of clicking over when I'm on hold, waiting for something to finish, etc.
I still hold out hope that a more privacy friendly, federated network will take over someday. But that's probably not going to be soon.