As an SEO, I'd stay away from social media personally... yes the uninformed customers will ask for it, but social campaigns NEVER produce what the customer expects it to. They hear "facebook has 300 million users" and then when only 4 of them "become a fan" of their product they blame you. If you're good at SEO, stick with that. The benefits of SEO will always outweigh social media and you should focus on educating the customer about that.
ESPECIALLY for e-commerce sites. Nobody says "Gee, I want to buy a widget today, lets see what I can find on Facebook"... they go to the search engine and type it in.
I understand the desire to branch out, but these things will also dilute your primary service. If you want to stay in the realm of related services, find a good SEO friendly web host (which offers dedicated IP addresses) and an e-commerce platform you're familiar enough with to optimize. Possibly merchant processing too. Those are good, related upsells.