Raul is your best option to stay in Madrid for a couple of days. His place is awesome, there you can feel how it is to live like a Madrid citizen. The location is great, near the train station (about 5 minutes) and not far from the metro station (12 minutes). I used the train lines while I was at the city and it was enough to get to the main places of downtown.
The hospitality was amazing. In the check-in Raul gave us tips about the city and about the house itself. The breakfast that was able for us was great and helped a lot. Oh, and the kitchen is avaiable to the guests so you can cook your own meal and save some money!