Guide Books and Maps
For German readers, we can recommend the guide books which are published in the Michael Müller Verlag:
The first section introduces the reader to the area (culture, history, landscape), the second section gives general information for tourists who will explore the country on their own and the last part goes into the details: sights, accomodation, restaurants - ordered by provinces and towns. Very useful books.
In Northern Portugal we used the cycling guide from Cyclos in addition:
The book was published in 1997, hence accomodation and restaurant hints are mostly outdated, but the route recommendations are still very useful. Though some height information can be found in the route descriptions, we missed height profiles like in the Siciliy guide. There might be an update of the book in the next years (volume 1 which covers the south of Portugal was recently updated).
The cycling guide Jakobsweg per Rad covers only the main way of St. James through the Meseta plateau (heartland of Castilia) such that it has almost no overlap with our route.
The best map that we found had only a resolution of 1:300,000 which is a bit rough for cycling, but covered the whole area from Santander to Porto. Spanish Atlantic Coast
Roads are coloured according to their traffic class such that one shall not accidently end up on a very busy road. The map lacks decent height information. Last, but not least scenic routes are marked green in the map which may make your choice for one route or another a little bit easier.