From the Office of Dusty Old Books
Starting with the smallest of the Big Books is Hayao Miyazaki and the Ghibli Museum which my wife gave me for my birthday last year. It's actually two books.
One is all the concept sketches Miyazaki made for the architecture and layout of the Ghibli museum. They're loose and dirty and a fascinating glimpse inside the man's mind.
The other book is all the concept art and final art for the exhibits therein.
Look at those cutaways! mmmm baaaby.
The book isn't cheap, but for a Ghibli and Miyazaki fan who loves the watercolor art and sketches just as much as the films, it's definitely something worth saving up for.
You can get it on Amazon here: LINK
-Jake