It was interesting to read these books. The first book is the source for the Disney films titled 'Freaky Friday'. In the book the mother caused the body switch, and the story is told from the perspective of the daughter in the mother's body.
The second book is about 'Ape's' (Ben's) attempt to fix a broken TV set. When he fixes it it begins to air shows 24 hours in advance, including live shows such as the news. The kids, of course, take advantage of the situation to try to prevent some things from happening. And there's the fun!
Book three is the story of Ben and Dad switching bodies. In this book the switch occurred as in the films, they had both just said 'I wish I were...' and the switch occurred. I enjoyed the last book the most. I suppose that is at least in part due to the fact that the story was completely new to me.
I love old Disney films and I also enjoy finding out how film adaptations differ from the original story-lines.