We have been 4 days in Madrid with 2 children (3 and 6 years) and stayed at Roque's apartament and we loved it! It couldn 't be more central! We walked by foot to the main known streets and we had metro and bus right around the corner.
The apartament was great, with everything we needed for our stay. Roque was very nice and friendly and gave us several tips about the city.
We will stay again there when we came back to this great city!:)