If you are looking for a list of characters, check post #13. It's a list of who is currently in the parks and their likelyhood of being seen. I just updated it this week. There are really two options for choosing characters for your books. 1) Put them all in (with a few generic pages for anyone you may have forgotten) and then take out the ones you didn't see when you get home. 2) Put the major characters in (say, the top 25 or the characters on the "Abundant" and "Common Characters" in post 13), and then add several generic pages at the end for everyone else. Be sure to include characters from any character meals you are planning to attend.
Some people just keep their autograph pages in the book as a souvenir. Some take the books apart and use them for scrapbooking or adding into their photo albums (Minnie's autograph next to a picture of you and Minnie). Some have even scanned them into their computers for including in digital photobooks or digital scrapbooking. I left mine as a book, and the boys and I like to look at them every once in a while.
ETA: I just saw that you are going to be at WDW during Star Wars Weekends (so jealous!!). Be sure to include the Star Wars characters in your book.
http://s143.photobucket.com/albums/r132/donatalie/Autograph Books/Volume 2/Star Wars/