We had a wonderful stay at Marta's apartment. This is very centrally located near Plaza Mayor. Our plane was delayed so we actually arrived on time. She had made arrangements for leaving our luggage if we had arrived early. Check in was a breeze. The apartment is very nicely furnished with enough space for a family of 5. I actually liked the 2nd bathroom better than the en suite. There is a Dia supermarket around the corner for groceries if needed. As noted by previous guests, the WiFi works well except in the bedrooms. There is a small European style elevator, but due to building's design, you still have to walk up or down a half flight of stairs.
Marta kept in contact with us and gave us great advice on local dining.
Plaza Mayor was a 5 minute walk. The rest of Madrid's central attractions were all with in a 20 minute walk. We also took the Metro which was very easy to use.
We were allowed to keep our luggage in the apartment after checkout as our train left in the afternoon.
TIP: The Tirso De Molina Metro Station is literally 1 block away. It is 3 stops away from the mail railway station Atocha Renfe.