I haven't seen much of Spain but I absolutely loved Cordoba, home of the Great Mosque/Cathedral. Whatever your religious beliefs, it is a wonderful building to visit. I think the Alhambra in Granada is worth a visit too and loved Barcelona, although it is some years since I was there. I think method of travel is key in Spain, there is quite a lot of boring bleugh between beautiful places if you are driving.
I saw an article recently about how vegan food is exploding in Spain - I think it was on the website of one of the UK newspapers, maybe the Guardian. I can't remember exactly but will have a hunt around and see if I can find it for you.