Definitely no suit. If anything that would be a mark against you. Marketing involves knowing your audience, after all, and showing up in a suit would appear a bit clueless.
Tailored and crisp, but still colorful, textured, and modern are all good. It should look dressy but still creative.
Aida has it--you want to look like you have a clue about the here and the now, and the future as well. Of course it depends on the specific position, but I have seen many, many people come and go for interviews where I work, and these are the commonalities I see in those who are most successful from a style perspective.