Live near San Francisco. Vacationed in Europe last several years (great trips) using Public Trans. Next year -> Spain, and I have done hundreds of itineraries, none of which I care for the flights (SFO to and from). But I have never considered Basque. Looking at SFO to BIO and returning MAD to SFO -> kind of happy with what I see (prices and TIME!). Will use Vueling or AVE trains to get around elsewhere.
So if the wife and I were to arrive BIO late September 2012, and we will be wasted when we arrive (the first night), and if we were to plan 2 more full days and nights, absolutely using Public Trans, where would we stay and what would we do? We love historical sights, shopping sights, good restaurants, a good museum/gallery (no more than one), and okay with a 1/2 or full day guided tour.