I post at least once a day, preferably twice, (prime time europe, prime time usa), having a discussion forum is great i can link to original content that you dont get anywhere else (most stuff on Facebook i see is just selfpromo or recylced news). I post old articles (2003/2004) to give them some social noise for google, works not bad, almost always see some ranking increase... 1.200 fans here
On the business side I force myself to post a once or twice a week just to keep my page active in case I decide to do something more with it.
On the family/friends account, I hardly ever log in.
Now if I was still single and in my 20s it would be a great way to connect with people briefly met at a party or bar that I found interesting to get to know them better. It is a great self-help dating service. No sweating it out before making that first date phone call. All you need to do is casually friend them on facebook and get a better feel on one's chances before taking the next step.
I update my facebook page as and when I have new content. The page enjoys around 2000 odd fans. Apart from publishing content from my site, I do ask an engaging question once a week to keep the interactivity going
Never. No facebook page. I considered joining earlier this year strictly so I could join a facebook page setup by for the purposes of reuniting with folks from high school that one of my classmates had set up. My best friend from that era (still my best friend, we've stayed that way for many decades) suggested it to me.
I never bothered though. I'm strictly uninterested in living my life online, publicly. My personal life is quite happily offline.