I know this thread is a couple years old, but G+ has a bigger role than ever before for local search.
In April 2014, Google incorporated Google Places into G+ and renaming it to Google My Business. This is now one of the most important citation a business needs to have online - especially local businesses.
Google uses information on your Google My Business page for it's search results - including hours of operation, address, phone number, etc.
Here's a tutorial I did on my YouTube Channel for setting up your Googl My Business page: https://www.youtube.com/watch?v=O2qmp6ofYOM
Also, getting reviews from your customers is another boast to your local SEO. Not sure how to get review on your page? Here is a nice little handout that you can give to your customers: https://www.whitespark.ca/review-handout-generator
While G+ might not be a popular social medium platform, and increasing your circles really doesn't mean much, claiming you Google My Business page is necessary for any local business and a first step for local SEO.