re: best marketing medium for a catering business

Think about the kind of catering business you are trying to attract: pick up, small lunches, big offsite events, high end social, etc. I wouldn't use the same strategies to attract the catered business lunch customer as the high end social/wedding crowd.

SEO isn't such a big deal if you're using other mechanisms to drive potential customers to your website. The website can be the "detailed" resource for the potential customer---the one you recruit through referral, word of mouth, or social media marketing, rather than the random google searcher.

The size of your operation should determine how much effort you put into things like SEO; why shoot to be the first google search result if you only have the capacity to handle 10-12 events per week? Generating more demand than you have the capacity to handle is a problem in a high-touch business like catering.