I recently made a trip to Madrid for both work and a vacation. I stayed at Ana's place which is really lovely and cozy. I definitely felt at home ! It was peaceful enough so I could work when I needed to and perfectly situated when I wanted to go out and explore the city.
The neighborhood is multicultural and so fun ! The apartment is close from everything - from the essentials (metro, grocery, restaurants, etc.) to the touristic attractions (5 minutes walk from Reina Sofia, 10 to 15 minutes walk from the Plaza Mayor, the Prado or the Royal Palace).
Ana is the nicest host. She makes you feel welcome, she is always available if you have questions (and at the same time she is definitely not invasive). She even graciously came to my rescue once when I foolishly locked myself out ! (Thank you again for that !)
I would recommend to any of my closest friends or any of you to contact her in order to rent her place if you ever think of going to Madrid. You'll have a blast !