Unless you happen to be in a very specialized niche, chances are Facebook or Twitter is where you’ll find most of your audience. Google Plus is ghost town unless you are chasing Web 2.0 weenies (or Google employees … yeah I went there). If you get traffic from other social sites and want to enable cross posting look into services like If This Then That to try to automate the process, and remove the grunt manual labor. Automate your primary feed and with cross posting, and scheduled posts from Hootsuite and/or Bufferapp you’ll be spending less than a hour a day publishing on social media. Thanks to services like Tweriod you’ll have some idea when those ideal times are, without having to be chained to your desk to reach your optimal audience. Just remember customer service is now an interregnal part of social media, use it as a contact starting point to take the discussion offline or out of the public eye whenever possible. It’s not that you’re hiding, it’s that you don’t need to broadcast every part of every customer interaction.
In my opinion having your links pass through social media channels, whether the links are nofollowed or not, creating the corresponding user data, and the developing trusted author accounts are the three biggest areas you have the most to gain from using social media, and again and in my opinion those are the three areas you should spend your time on.