We had a very nice stay at Ana´s and Hugo´s Place. Even though we didn´t get to meet them, the Contact was very good and they gave us many helpful information for our stay in Lisbon.
The Flat is located downtown at a nice area with many cafes and bars. We didn´t have to use the metro because everything was within walking distance.
I can recommend to stay here if you´re planning a trip to Lisbon!