I lived in Spain off and on in college and in graduate school. I was enough of a boy from Wisconsin that I drank more beer than wine. There were two standard Spanish beers--Aguila and Mahou (pronounced like Chairman). Mahou is a pale ale and very good fresh (on tap). Aguila was a so-so lager. A neighbor of mine tried to find Mahou over here because he had been really enamored of it when in Spain on his honeymoon and asked around at Sam's and some other places. This is hearsay, but he said he was told that it couldn't be sold in the States because of pasteurization laws.
I don't remember any darker beers when I was there, but it was a wine culture rather than a beer one for the most part. There have probably been a dozen small brewers who've sprouted up in the last ten years since I spent extended time there for all I know. I would suggest, however, being open to wine and sherry. I regret having stuck too much to beer when I was there, and Spanish wine has really come into it's own in recent years. And if you're in southern Spain you've got to have sherry and some local almonds or olives--especially at 6 in the afternoon between comida at 2 and cena at 10.
That all being said, my suggestion is, if you're looking for something to wash down morcilla (blood sausage)--Mahou is your best bet.
Have another. It's 9:30, for God's sake. ~Roger Sterling