I would say the autograph books are at least 4x6 possibly 5x7, they are pretty good size. The passport books for Epcot are definitely smaller and they come in a clear plastic "case" which was nice for keeping them in good shape.
Thanks for the quick reply!
Me and the boys made some - their Nana bought them cloth covered books and we decorated them with stickers. They are 9 x 7.
I wanted to keep it small-as I would like them to carry them themselves.
I think that we will just use those as trip diaries.
My husband had characters sign his baseball hat this trip (a sharpie pen is a must). Nothing to carry around,,,he just popped in on his head and away we'd go. If your boys wear hats that may be an idea so they/you don't end up carrying the books around all day.