My all time favorite Disney book is In Service to the Mouse by Jack Lindquist. I've read it several times because I just really enjoy some of the specific stories that make up the history of Disney.
I've read probably 30 books on Walt Disney and the Disney company. Many of them are either informative but just so dry, or fun but with little substance. Lindquist's book was both fun and informative.
Are you looking for history of DL? WDW? The company in general?
In terms of books about the business practices of the parks:
(in no particular order)
- Creating Magic by Lee Cockerell
- Wonderful World of Customer Service at Disney by J. Jeff Kober
- Be Our Guest (official) by the Disney Institute