I would very much recommend Luís's place. Luís was busy with working during my stay but I was met by Teresa, who gave me the warmest of welomes and was always there to help throughout my stay. Her love of Lisbon really came through!
The room is well looked after with a large window to let in lots of light. The flat was exceptionally clean and the other guests were a pleasure to meet.
The location is great! On the edge of the centre, a short stroll from Bairro Alto and within walking distance of all of Lisbon's main sights. For a city changing as fast as Lisbon, Santos retains a refrshingly local feel. Admittedly, this can make it noisy at night (and probably not the place for those who seek peace and quiet) but I adored it! I felt immersed in the daily life of the city and would definitely stay again.