We got both kids a book of their own. The book seems really good. It starts off with tips for visiting WDW, then has a section with scavenger hunts: they can check off which color monorail they saw or rode, they check if they heard certain phrases around the world like "Please stand clear of the doors," and various other things they can look for. Then the book tells about each attraction with pictures, a brief description (including certain things to look for in the attraction), whether it is scary, and a space where the child can rate the attraction. After the book covers each attraction, there is a section where the child can journal about each day. It is really child friendly. The journal has an area where they can tell about the weather and temperature for the day by circling a picture of a sun, a sun behind a cloud, or a cloud with rain falling from it. Lastly, the book has a section for character autographs.
The book is a little heavy and I'm guessing about 11" x 8". If you carry a backback or bag in the parks, it would fit in those. It would not fit in a fannypack. Hope this helps!