Is Alarcón beyond Cuenca (the city) toward Valencia, or nearer Madrid? Sorry, I don't have a map handy. The Posada San Jose and Hotel Leonara de Aquitania (I've mispelled it) in Cuenca are charming possibilities, although not castles. I wasn't able to use the link to the latter. I think they may both be recommended in Alastair Sawday's Guide (and you know how I like it).