Do a thread search and you'll find pllllllllllllenty of arguments about D23 being worth it or not.
To answer your other question; some very good books are the two books about Disney Imagineering...
Walt Disney Imagineering: A Behind the Dreams Look at Making Magic Real
Walt Disney Imagineering: A Behind the Dreams Look at Making MORE Magic Real
The "more" book was just released this past week; both are chock full of concept art, photos, and text about the parks.