I second Bilbao. I've never been but I've heard it's developing into a culturally rich centre. And of course it has a Guggenheim museum.
Toledo, Salamanca, Segovia and Avila definitely not to be missed. I went to those places on coach trips from Madrid when I lived there. Of course we stopped for lunch but (a) it was over 40 years ago and (B) even if the places we had stopped were still there, they would be places to avoid as you don't want to eat where coachloads of tourists are catered for.
I know Andalusia better but the Basque country and Galicia will surely have lots of bodegas too, where you can get a light meal and/or a refreshing drink and sit outside and watch the world go by. I used to love drinking a glass of the light cerveza at lunch time.
Sounds like a brilliant tour.
