I enjoyed my stay at Juan Carlos's place very much.
It was less than 30 minutes walking from terminal 1 so just follow Google maps, faster than waiting around for a bus but if you have luggage, you can take the 101 bus which gets you very close.
The room is spacious, well ventilated, bed comfortable, wifi strong, bathroom clean with great water pressure. Kitchen spacious and clean as well.
Perfect for any amount or kind of stay but if you want to be close to the airport, you can't find a better place to be. Juan Carlos was warm, welcoming and helpful as well. I hope he is around for the next time I fly through Madrid!