This is a good question.
It is definitely optimal to have both SEO and search marketing activities – they should feed each other. The right balance is going to be more influenced by your site format than by the fact that the niche is Bingo. If you have a traditional article/review portal then SEO is where you should put your focus. A magazine style format would benefit from twitter, css and social bookmarking. I think that a more interactive site will benefit most from focused social marketing activities.
I think your success is going to hinge most on your own elbow grease. Even if that elbow grease is spent weeding through the marketing opportunities. Realizing that on the internet marketers and network success, which should be measured by your success, is more often measured by charging as much as possible for as little (effort) as possible.