Over at GalleyCat they have a chat with Laura Miller on book reviews, but the point that interested me was her comment on how literary authors can try to engage readers--make their characters desire something.
Maybe a character motivated by desire is pretty damn obvious, but sometimes someone has to state the obvious. Quest stories function so well because they focus on this desire, its frustration, its success. Maybe a romance novel is a quest? everyone, even the reader, is pursuing the tantalising prospect of a happy ending.