I have 55 characters so far. We have a party of five, including two princesses and a first time adult who i think will be doing the autograph thing, too. I have all the princesses, Super Six,
MNSSHP characters, and probably all major movie characters: Aladdin, Genie, Jasmine, Jafar, Flik, Incredibles, Lilo, Stitch, Monsters, Winnie the Pooh and Friends, Toy Story principals, Storm Trooper, Darth Vader, Wreck It Ralph, Vanellope.
I also have passport pages for Epcot -- I want them to collect the passport stamps and have the CM write their name in the language of their country. And I found one for BBB that I will have the fairy-godmother in training sign.
I'm still looking for more characters to add...I figure it's easier to have them than to not have them and need them. I also want to include a bunch of blanks -- which will have either a mouse ear pattern or a park resort background.
Like you, I don't know if we will want to do a lot of characters or not. We are taking a 6 YO and 8 YO girls, and I believe the characters will be a big hit, so I ant to be prepared.
The cost of the autograph book keeps increasing with each page. Once you make the decision to go WDW, it's hard to argue about saving cents when most everything else you're spending is dollars. But I think this will be a very tangible souvenir that the girls will keep for a long time.