All these sites are just tools for interacting with others – they are what the user makes of them. I stay on top of my privacy and preference settings so that the annoying stuff is minimal.
I just opted-out of Google+ and its Shared Endoresements and Targeted Advertising. I periodically go to Facebook’s Blocking tab and type the first few letters of common words in games and apps – like “bubble”, “farm”, “casino”, “poker”, “war”, “ville”, etc. – which brings a popup of the most popular Apps and I go down the list and block them.
Decide what purpose these sites/apps serve in your life and go through the user options to tailor the experience to your purpose. FB is best for maintaining contact with people and businesses you already know. G+ is better for connecting with people based on common interests. There is a lot of overlap, though (and as I write this, I realize that I haven’t used the G+ community pages much, and that might be a good resource for my personal health concerns). Instagram is a bit of overlap, but tied to photo or video imagery. IG recently added the ability to share content with just specific people as an added privacy measure, which I appreciate; but they still have a long way to go for user experience customization, though.
If you want to improve your activities off the net, then you can still use those sites to find places in your area that you might enjoy visiting. Another resource that I often recommend is Meetup.com, which is a site that allows people to organize get-togethers based on common interests.