You might want to take a look at a book by Birnbaum's called Walt Disney World By Kids For Kids. It is the "official" Disney touring guide, so there are a lot of full color pictures and character graphics. It also contains park maps that are virtually identical to those handed out in the parks.
I bought one for my (then) 3 year old, even though I knew he wouldn't be able to read a word. He still loved the pictures and maps. I bet an 8 year old that has bever been to WDW would really enjoy it.