I have (in the order that I
them and/or find useful)...
Planning
Passporter (If you have to get one...get this one)
Unofficial Guide (If you can get two...get this one too!)
Background Info
Imagineering Guides (MK, Epcot, AK...and waiting for DHS)
The Complete Walt Disney World (I know some consider this a planning guide..but I think it is lacking planning info. I do love the extra info and the gorgeous photos though!)
Kids' WDW Books
Guide to the Magic for Kids (absolute gem of a book of all things WDW for kids, lots of extras, journal pages and dd (6.5yo loves it!)
Thanks!
Birnbaums For Kids, by Kids (really thin coverage of WDW, about 1/3-1/2 of attractions covered, nothing extra for kids...The only book on this list that I think was a thorough waste of my money.)
Extra fun stuff for WDW
Hidden Mickey's / The Lost Journals (I love both equally. They are great for "things to do in line" activities.)