Hi
I travelled to North Spain and Portugal last year - it was my first overseas trip.
I had my route fairly well planned beforehand as I had booked and paid for my accommodation in various travelling lodges & B&B's beforehand. I like a good bed, some decent food and wine at the end of a hard day's riding. Try -
http://www.estalagensdeportugal.com/default_en.asp
I didn't need my sat nav as I wrote out each days itinerary - road numbers, places etc on a small piece of paper and stuck it to the inside of my windscreen using scotch medical tape (it comes off easily without leaving and marks).
The road across the mountains between Spain (Leon) & Portugal (Zamora) are truly amazing and free of traffic.
Beware toll roads. They are excellent quality and fast but can cost you as much as your fuel if you aren't careful.
Ferry to Santander at the end of August had about 60 bikers on board so the trip was fun.
Hope that you have a good time.
Zara