I often have people asking me how much time they should devote to their social media and online presence.
Personally I think it is a job in itself or one that could be added to your marketing managers job description. Best solution is to consider a Wed Design / Management position. Ideally, if you are using your social media correctly, you should be 'herding the sheep' to your website; generating traffic. This involves adding new content to your website by updating a blog worth sharing, adding pages, discounts, or company news. So yes, the two really do go hand in hand.
Because social media is such a NEW and unexplored industry with huge growth while always evolving, it is hard to find people who really know how to use it effectively. What I know I learn EVERY DAY on the job and finding a fellow administrator who's @tagging and posting in a neat manner with a goal in mind, really makes my day!
I have followed corporate companies in search of the 'right person' for the job. Often they start by hiring an intern only to realize they put the online voice of their company in the hands of that intern... Without being reckless or irresponsible, I would say the person who knows best is often the small business owner them self. Other key-players with knowledge of the industry could also work, so it makes most sense for THEM to do it.
In addition to that I would suggest hiring a marketing consultant who manages active social media platforms showing constant growth while staying up-to-date with current trends. Get this person to rather train someone in-house who knows the industry and add it to his / her job-description. Again, understanding that technically this is a job in itself that should by no means be disregarded as something 'done for fun' or in your 'spare time'.
I have seen huge corporate companies advertising for Social Media Manger positions over and over and over without success month after month. The highest I have seen offered so far is $108 000 per year. This should be a clean indication of the value they attach to this job.