Finding good books about Disney is actually very hard. Most books are either company sponsored puff pieces (like Eisners biography) or are the usual tracts about how Disney is an it effort to prop-up the white male American agenda and quash the freedom loving granola eating bunny huggers.
On the business side is Storming the Magic Kingdom by John Taylor from 1987. It is about the corporate greenmail scandals that rocked the company and the takeover by Roy Disney and the Bass Brothers. And they in turn hired Michael Eisner. The book is written as a business book and from an outside & independent perspective. Reading it will definitely give you a different take on many discussions here on the board.
On the parks the best Ive seen is Designing Disneys Theme Parks: The Architecture of Reassurance edited by Karal Ann Marling. This is a somewhat scholarly work that accompanied an exhibit which traveled to many art museums. The book is packed with behind-the-scene sketches, drawings and plans. You will find yourself amazed by the WDW that might have been. But the books text is also extremely insightful and explains Disneys unique architecture as storytelling approach. It also explores the impact of the Disney style to the world outside the parks, and how that has in turn affected Disneys approach. Overall an excellent work.
The best company book is
Disneyland: Inside Story by Randy Bright. He was a long time Imagineer (one of the best), having worked his way up from the Disneyland itself. The book is a history of Disneyland told by the people who designed and operated the park. It has many stories, debunks and few myths and reveals a few little known events. Anyone who thinks Walt was nothing but a businessman who built cheap will have a very different opinion after reading the book.
There are others that I still have to locate in the vast AV Archieves of Knowledge. A more critical book is called Vinyl Leaves and is about Disneys impact on Florida and American culture. There is another book that Ive forgotten the title the argues Disney was a major stabilizing force in American society as the country moved from rural to urban/suburban between The Great Depression and Vietnam.
I will continue to dig and post more discoveries as I come across them.