Good point about the relative cheapness of maps
When you are in the Picos, have a look at what the local garages and paper shops have on offer. It's often possible to pick up very local maps and / or maps with a better orientation quite cheaply.
Whilst it's a crude map, I would certainly suggest getting a copy of ADAC's touring map, with some very good suggestions on roads to drive whether on a motorcycle or in a car.
http://www.mapsman.com/store/product.php?id=495