SEO doesn't necessarily mean that the person who is doing your SEO will create social media sites on your behalf. As you know your site better (or product) it would be more useful for you to create your own social media pages, and then apply professional SEO as they may also use your FB/twitter pages in their marketing tactics.
It is not necessory that after doing SEO, SMO is the must activity to do with your website. When your website SEO work is not satisfactory then go with SMO.
You try twitter, facebook, linkedin, etc... are used for smo is best way to get traffic and very useful business are benefit. Google+ is best try to create community.