juju, I just don't know what you're after, because I'm after that as well. I also want to take a book, a meaningful book... True, you may not have time to read, especially if you walk long stages. But if your stages are short, 20 ks and under, then you will definitely have time.
Phil Cousineau's The Art of Pilgrimage is a fabulous book. It's a great idea, Sil. I just don't have it here with me. On the Camino itself, in Eunate, one year, I found Fr Hurley's book. A priest who walked from Roncesvalles or SJPP, wrote 33 small chapters, each with a symbol from the Camino. A fabulous little book as well.
If you speak Spanish, the Benedictine Brothers in Rabanal also sell a light book of reflections on the Camino, but that's closer to the end of your Camino.
I am hesitating between Christine Valters Paintner's The Artist's Way (spirituality & creativity) and Joan Chittister's The Rule of Benedict, because I have been reading it for years and the more I read it, the more I find things in it.
It is also true that a good guide book is a fantastic companion, as I find I spend a lot of time reading the information in it, or planning the next days...
You will certainly find books in the albergues, left by other pilgrims, and so you continue the tradition of reading and passing on.
I also know that I have taken books with me that I left on the Camino as I found one better suited for me at that time there...
Let us see what others have to say about it.
¡Buen Camino!