Even though you did not specify, I am going to answer this from an SEO perspective. Of course you should not overlook Facebook and Twitter... maybe Pinterest depending on the business. However, G+ has become absolutely crucial in regard to your business website's SEO.
Even though no one seems to dig google+ very much, it is still very important to google. You should make sure to get a google local page and connect it to a google+ for business page. Update the page as often as you would a facebook or twitter. You should also use the rel=author tag in your blog posts/ website and put a link to your G+ Business page on the website.
This will ensure that your photo (or business logo) will show up next to your listing in google search results. It will also show a photo in places results which often show up in normal google searches for businesses. (Not many businesses have figured out that they can get the photo to show in regular search results, let alone places results-- so this will most definitely help you stand out.)
Make sure to fill out all profiles completely. Add all the photos and videos you are allowed using your target keywords, of course. An added bonus is that since google is biased toward Google+ it will reward you in search results, even thought they act like that is untrue....