Stephanie - would you say that in This Is Not My Hat, that it a story told from two points of view (the little fish and the big fish) rather than the big fish's story being a subplot? Both parts seem equally necessary for the story, while I've always thought you could take out a subplot and still have the main story intact (not as wonderful, perhaps, but intact.)
I'm wondering the same for Officer Buckle and Gloria - Gloria's antics in the background are really key to the story, in a way that the mouse's actions in Goodnight Gorillas are not, though they add depth to it.
Franzilla- thanks so much for the link - very helpful!