Will Gooogle+ fit the bill?I think it might. My first impressions give no cause for concern.
CirclesUsing the metaphor / analogy of circles of family, friends, acquaintances etc. everything becomes quite intuitive. You set different sharing settings for each circle so the "heads" you drag and drop into each circle can get a different set of your "shares".
Adding new circles is really easy, as is managing who's in which circle (and of course someone can be in more than one circle).
Streams per circleAgain, this feels like a natural way of doing things - keep an eye on what your friends from the pub pool team are up to, or the latest stuff that happening with family.
And if you decide after a while it's not for you, you can download your data and then remove the service by deleting your Google profile from your account. I'm not sure about the ramifications of this, though. It sounds fairly major.