I highly recommand "the Lisboeta" ! The flat is really charming in the heart of the Alfama, it's perfect for a couple.
Cecilia and Pedro are very great host. They recommanded us some good places for eat and visiting in Lisbon and we passed an amazing time in Lisbon thanks to them. More over, they are very accomodating and always ready to help. To sum up, everything was PERFECT !