When it comes to a plot, like anybody I want a story that hangs together — and for me it is so satisfying to get to the end of the book and find that all of the subplots were intrinsic and pivotal to the main plotline. However, when it comes to a plot, what I most cherish is surprise. This is a consequence of my many years working as a motion picture story analyst. At the rate of 5 novels or 10 screenplays per week, I read and critiqued materials submitted to movie studios. After several years of this, you’ve seen it all, plot-wise. That was a long time ago, but unfortunately I still anticipate most plot twists. Sometimes I like an otherwise mediocre movie just because it has some story element that I didn’t see coming. I am less charitable with mediocre novels; I suppose that is because my emotional investment in a novel can be so much greater.
One of the (many) things that hooked me on the Potter books was how many surprises J.K. Rowling conjured. I think I was in book 5 before I anticipated a single surprise. Ahhhhhhh.