Did I leave any other important ones off?
Do you actually update your facebook, twitter, etc?
It's already a lot of work maintaining your website and/or blog.
I, imho do not like stale content. I see many businesses' sites that never update content, change photos, update the blog, post on fb, etc.
I'm thinking of just sticking with the main ones people use and try and keep up with the trends as they come and go.