I'd say talk about "Reverse-Engineering Visual Design". As a coder who understands some of the basic principles of design but just can't seem to make it click,

I'd say talk about "Reverse-Engineering Visual Design". As a coder who understands some of the basic principles of design but just can't seem to make it click, that would be the most interesting for me. Optimization and SEO are nice, but if you don't have a solid design they're not that useful.