We stayed 4 nights in Madrid at Li Castillas and were extremely pleased with the size and cleanliness of our room and the helpfulness of the staff. It is very central - we walked everywhere but had the option of taking a metro from 3 different stations only minutes away. There is a very nice restaurant attached to the hotel as well as many other great places to eat nearby.
Quiet location even though I was at the front on the first floor and it is only 2 minutes from Sol and the Gran Via in the bustling heart of the city. My room was a bit on the small side for a double and the breakfast is a little limited on range of items, but then I was spending so much time in the bars and restaurants in the evening that these were not a problem. If you like lounging for hours in the room, this is not the hotel for you, but then again, perhaps Madrid is not the place for you either! Great hotel for the price.