Last night I posed this question on Twitter: Do you prefer a book that makes you laugh or cry?
Several people said "laugh." But most people said "both." (Crying, by itself, didn't get many votes.)
I've been thinking about that message: both. I think we appreciate books that have the emotional richness of life. In life, we often share a smile or a teary laugh even at funerals; we may feel a pang of sadness even at the happiest times. We deal with tragedies and comedies back to back, and sometimes simultaneously.
It makes me think that a good test for a writer to apply to a manuscript is this: Does this story hit only one emotional note--and if so, is that what I really want? Or does it evoke several different emotions?