I have been included in one group. Family. Period.
Facebook has as much value to me, these days, as MySpace does. MAYBE a tad more if you include the fact that it seems to be the preferred method for my family to keep in touch...they all like the various "ville" games, anyhow. I don't, but hey, I keep up on all of the prayers and "Jersey Girrrl" sayings and the like. It amuses me.
For everything else I use G+. MUCH more "targeted" when I have something to say, or if someone has something to say to me.
If I were in a position to "do business", I might look into such things as "LinkedIn", but working once a week or even every other week is fine by me. Remember, I'm disabled now, so it really is "pin money". NOT to confuse that with "Bottom Feeder" or "CHEEP" or any of the other derisives, just...mmm..."selective".