We had a wonderful stay at Victor and Yoli's apartment. It's central to all the important sites that you can even walk back home for a short rest before venturing out again! We had everything we needed to feel at home (including if you need to cook). Carrefour Express is a 2-minute walk away and for medical emergencies, one of the oldest pharmacies in Madrid is near there too. The street is relatively quiet even when the restaurant next door is full - you do get a little bit of noise especially on Friday or Saturday night but it's nothing to complain about because it's not "rowdy."
It's worth a mention that the beds in the apartment were comfortable, I wanted to sleep in most times! :) If you feel like lazing about at home, there's always Netflix.
Both Victor and Yoli were very responsive, accommodative, very friendly and helpful. A very minor issue was attended to promptly and Victor himself popped in to help rectify it. Thank you, Victor and Yoli. We will definitely come back.