I strongly recommend Elsa's place. Firstly, because it's quite well located only a nice walk away from most touristic spots, tram and bus stops and last but not least, it's close to the traditional Pastéis de Belém (yummy). The house by itself is very nice, cozy and it got everything you need. And Elsa was a great host, very kind and helpful giving us a lot of tips about what to do, where to eat, etc...
Thanks Elsa, I felt like home! =)