My stay a Markus's house was really enjoyable. The place is nice, in a lovely neighborhood and in a really perfect position: only 10 minutes walk and you find yourself in the heart of Wien! Besides the metro was just around the corner.
The comunication with Pia (who assisted Markus) was always fast and really of help (she was so kind to give me all the information I nedded to get there from the airport for example). The chek-in and check-out were really practical.
I would recommend this place for everyone who want to be in a tactical position to discover Wien.