Specifically for older attractions look for WDW - Then, Now and Forever and Since the World Began - WDW the first 25 years. The field guides are okay but don`t offer much historical detail.
Or take your pick:
Project Florida, Walt DIsney Productions 1967. Not commercially available
Master Planning for Walt DIsney World, Walt Disney Productions 1969. Not commercially available
Preview Edition Walt Disney World, Walt Disney Productions 1970
Pictorial Souvineer of Walt Disney World 1972
Pictorial Souvineer of Walt Disney World 1972 2nd ed
Walt Disney World a pictorial souvineer 1983 WDP
The Story of Walt Disney World, Walt Disney Productions 1976 2-76-3
Walt Disney World: The first decade 1981
Walt Disney World EPCOT Center, Walt Disney Productions 1982
Walt Disney Worlds`s EPCOT Center - Creating the new world of tomorrow 1982 0 8109 0819 0 1st ed
A pictorial souvineer of Walt Disney World 1989 Disney 0127 100005 1189
Walt Disney World 1989 Disney w0127 10003 989
Walt Disney World 20 magical years Disney w0127 10003 1190
Walt Disney World 1994
Since the World Began 1996 07868 8219 0 (pb) 6248 3 (hb)
Building a Dream - The Art of Disney Architecture 1996 0 8109 3142 7
Walt Disney Imagineering 1996 0 7868 6246 7
Designing Disneys Theme Parks - The architecture of reassurance 1997 2 08013 639 9
Walt Disney World, a souvineer for the new Millenium 1999 0 7868 5406 5
What would Walt do? An insiders story about the design and construction of WDW 2001 0 595 17203 2
Disney the ultimate visual guide 2002 0 7513 3913 x
Designing Disney (John Hench) 2003 07868 5406 5
The Haunted Mansion 2003 07868 5419 7
Pirates of the Caribbean 0-7868-5630-0
Roller Coasters, Flumes and Flying Saucers 0-9657353-5-4
The Disneylands that never were
www.lulu.com 2006
The Imagineering Field Guide to the Magic Kingdom 0-7868-5553-3
The Imagineering Field Guide to Epcot 0-7868-4886-3
Vinyl Leaves 0-8122-1472-0
The Making of Disneys Animal Kingdom Theme Park 1998 0 7868 6402 8
Inside Disney 2002 0 7645 6443 9 2nd ed