I make photobooks for my girls to use as autograph books. However, we had APs this last year, so that made it easier (I used photos from previous trips to make the books). To make the books, I start with photos of my girls with characters, add Disney clip art and try to make them look kinda like scrapbook page designs, with a place for the characters to sign. You could do the same type of thing with just clip art if you don't have pictures. Then, I wait for a really good sale (such as a free photobook offer from Shutterfly) and then order the photobook. The characters really like the photobooks! Even the non-face characters (you know, the fuzzy ones) usually flip through the books to look at the other pages.
I would suggest including any of the following characters that you would like to meet:
Mickey
Minnie
Goofy
Donald
Chip & Dale
Alice
Mad Hatter
Pinnochio
Geppeto
Pooh
Tigger
Eeyore
Woody
Jessie
Buzz
Queen of Hearts
White Rabbit
The princesses (Rapunzel, Tiana, Ariel, Snow White, Cinderella, Belle, Sleeping Beauty - oh, and I hear Merida is now in the parks near IASW)
Peter Pan
Jake (from the Neverland Pirates)
Handy Manny
Fairy Godmother
If you're going to a character meal, then you may want to ask to see who others have met at that venue (for example, we met Hook and Rafiki at Minnie's breakfast, but I haven't seen them elsewhere in the park)
Ones not to include because they don't sign:
Duffy
Sully