I run three businesses, including Matt's jewelry shop here, and in my research and after trying out FB pages, I quit using FB for business visibility and engagement. Edgerank is a problem, as was the the way FB did search until very recently.
I agree with Heather's comment that folks seem less likely to be in shopping mode on FB. Also, the young people are leaving or minimizing their use. I've seen other articles on this as well as seeing it in my family.
The main thing I use FB for right now is groups about things I'm interested in. I'm hoping that I can grow some community stuff on Google+ instead. G+ is smaller, but it's where the younger guys are, and a lot of Matt's coin rings are more for the male crowd. I'm also an editor by trade and have run a freelance editorial service for many years.
My visibility priorities are: Shop/site, blog, then social media. I pick the ones that fit me/us and our products/services (for example, Twitter has active interest areas for my editing stuff, Pinterest is good for Matt's coin rings, Google+ is kind of my catchall). I really think it pays to check out the different social networks and just find two or three that resonate with you. You won't get much out of systems you don't enjoy (like Twitter has that 140 character limit and you need to post several times a day, whereas the others have more space, you can post pics directly, and you don't have to be on there all the time). It really pays to do research and then be selective, I think.
And most important is to make cool stuff and keep a good shop! Social networks are just marketing and customer engagement outposts.
Joanne, MMM shop manager