I'm on facebook where I occasionally share a picture of my son or a picture from something I enjoy. I don't post often but this way my parents en grandparents can see my son growing up. Don't actually care if my 'friends' see this.
When I'm on the toilet I sometimes take my iphone and check the FB stream. Check it when I don't have much time or feel like investing a lot of effort in reading something.
Just use it like you want to use it. This whole social network hype, like you can only be social online. People have been social even before the phone was invented. It is just another extra tool and doesn't replace normal social interaction. It never will!