Thanks! Yeah, it is a big area to cover. If we do Portugal, it will only be a short 7-10 day jaunt, with most of it saved for future. We are thinking of doing bases as you suggest--although I believe DW is looking at more like one a week, rather than 3-4 for the whole trip. Which parts of the Interior did you visit? The Basque region in the North had grabbed our attention.
We have traveled by train from Barcelona to Montserrat, Valencia, Madrid, Segovia, Toledo, and Sevilla.
The Northern part of Spain, namely the Basque region (San Sebastian, Bilbao), the Asturias autonomous region (Oviedo), and Galicia (Santiago de Compostela), is not served by trains. You either have to take a flight, or sit on a regional bus. I chose to drive. The Northern part of Spain is beautiful, and the culture a bit different than the southern part of the country.
I had always wanted to visit Asturias, ever since I fell in love with the musical piece called Asturias (Leyenda) by Isaac Albéniz (1860-1909). And curiously, it was written for the piano, but nowadays is well-known as a classical guitar piece.
In the southern part of Spain, I have also visited Cordoba and Granada. I was in Cordoba during the Flower Festival. In Granada, I was able to register a few months in advance to visit the inner palace of the Alhambra. This hilltop castle, I also knew through the famous guitar piece: Recuerdos de la Alhambra (Memories of the Alhambra).
On the Mediterranean coast, we have visited Cartagena, and the small town of Alcosebre. These places are not as unique as the other locations.
In Portugal, we have visited Porto, the Douro River Valley, Lisbon, Sintra, and Coimbra. It was by driving.
Just scratching the surface in these countries, and I hope to come back for more.