Reddit mentions of The Vault of Walt

If you want a book about Walt in general, I suggest "The Vault of Walt" by Jim Korkis. It debunks some myths about Walt, while also telling you about his personal life, and projects for things such as Disneyland. It's a great read for any Walt Disney fan, like myself.

Jim Korkis - The Vault of Walt

This guy is a walking Disney encyclopedia, lots of great stories from his work there.

I definitely agree with /u/claremontfish that the Imagineering book is one of the best.

Some other good options are:

• Walt Disney's Imagineering Legends and the Genesis of the Disney Theme Park - Takes you through some of the different Imagineer positions, how they do things, and some of the most famous Imagineers.
  
• The Vault of Walt - All sorts of Disney history, from the movie making to the creation of the parks and rides.
  
• Four Decades of Magic - Stories about the creation and running of WDW, in 28 essays by some of the best Disney writers and historians. For example, one follows the challenge of creating WDW in an area previously filled with swamps and forests.