1) Musical History of Disneyland (6 CD Set)
2) Pirates of the Caribbean ride soundtrack (Disneyland Theme Park Exclusive) (Can only be found at Disneyland)
3) The Haunted Mansion ride sountrack (Disneyland theme park exclusive)
(Can only be found at Disneyland)
4) Haunted Mansion Holiday ride soundtrack
Some of the best hard-to-get stuff from Disneyland/Vista Records is now at iTunes Store too:
Annette's Beach Party
Babes in Toyland
Let's Get Together with Hayley Mills
Camarata/Darlene: Alice in Wonderland
Saludos Amigos (instrumental version)
The Mickey Mouse Club
The Mickey Mouse Club Serials
I would second the motion to both A Legacy In Song, and Disneyland A Musical History.
I would also suggest that you pick up some complete soundtracks. Mary Poppins, Jungle Book, The Little Mermaid, Pinocchio, Snow White, Beauty and the Beast, Bedknobs and Broomsticks as these complete soundtrack recordings are great.