It reminded me of a presentation I attended at a conference last year where an editor said one of the key things that stands out to her in a query letter is if the story offers something that makes it different than other books out there in the same genre.
I would assume there is a fine line between the unique attribute and a gimmick, but if it's something that really enhances the story, then all the better for marketing purposes. Some examples that come to mind from best sellers are: vegetarian vampires, the story of the rape and murder of a young girl told from the dead victim's perspective, and World War II England seen from the perspective of Winston Churchill's dog.
My current story doesn't have a graham cracker angle. Does yours?