One thing that gets me is that only the first four Narnia books have ever been dramatised (the BBC went as far The Silver Chair back in the 1980s).

It remains to be seen if Disney goes beyond The voyage of the Dawn Treader. I understand that they have the options.

The Magician's Nephew explains how it all came to pass.

The Horse and his Boy was actually written before Silver Chair though was the 6th to be published. It is a story set mostly outside of Narnia after the events of the first book.

The Last Battle contains Lewis's Narnian eschatology and is probably easier for adults to understand than children and can be very dark in places.

Looking how long it took to bring Tolkien's three books to the screen I wonder about the remaining four Narnian chronicles...