Highly recommend Pedro and Ruben's place in Bairro Alto. Excellent location, clean accommodations, and the best host. Ruben went the extra mile to give us local recommendations, feedback on our own itinerary, a local tour and even made dinner reservations on our behalf at an amazing Fado restaurant. Also, the place had space heaters which saved us in the cold evenings.
Note that the ceilings on the second floor are slanted, so it can be a bit tough for tall people. Also, there is no elevator and very narrow stairs - pack light if you can!
We would definitely stay here again!