If a film is coming out, I wouldn't then try to read the book first.
This. I have never done that. In fact... now that I think of it, there are very few times when I've seen a movie and it made me want to go read the book. The Trial
is a notable exception. It's one of my favorite movies and the book (and all of Kafka) is now one of my favorite books.
But that's a rare case. So to answer the poll question, I guess in cases where I've experienced both, the book usually comes first. And a book is more likely to make me want to see the movie than vice versa.
Also any surprise if its intrinsic to the enjoyment of the book means it aint much of a book.
This too. Surprise can be a key element to a reading experience, but if the book is written well, then surprise won't be the ONLY element that makes it worth reading. I feel that "spoilers" are much more likely to sour a viewing experience than a reading one.