Staying at Rosa's is the best thing that could have happened to me for my first trip in Madrid/Spain.
Her place is central, located next to a metro station and really close to the main museums of Madrid (Prado, Reina Sofia, Thyssen). I enjoyed the calm atmosphere of her house and the feeling of security/safety it provided.
As for Rosa, she's very attentionate (she made me a coffee at 06:45AM!!!) , joyful and well-learned about art history and the general history of Madrid. Her knowledge and advice were very helpful as my visit was quite unplanned.
I definitely recommend Rosa's place!