I highly recommend David's place. It is really centrally located--I didn't once need to take the metro during my 3-night stay as every destination was walkable. I also appreciate how flexible and kind David was when my flight to Madrid was significantly delayed. It made a huge difference. The room is wonderfully decorated, with tons of space to tuck away your suitcase and belongings, and there is a private guest bathroom. David left out great recommendations for restaurants and cultural sites a block or short walk from the apartment. Definitely a great place to stay--I hope to return during my next trip to Madrid :)