Shit. I loved John Crowley's work. Even, perhaps especially, some of his earlier novels.
I consider 'Engine Summer' to be a true masterpiece of complex, layered storytelling — better even than 'Little, Big' while being a quarter of the word count. I can go on at length about why, but I doubt you want to a fifty post thread in your mentions.
I can say I've read it at least five or six times and every single time I was crying on the last page.