We stayed four nights at Hotel Convento do Salvadore and used it as our homebase for exploring the Alfama area, and going to see Sintra and the rest of Lisboa.
It was absolutely perfect, the rooms are small, but tidy and well thought out. They have doors that open to a fresh air patio and have a lovely breakfast. That is an additional €6 per day but well worth it. All of the staff were excellent, helpful, kind, caring, and spoke perfect English as well, which was a nice help for us since we only know a little bit of Portuguese. Highly recommend- would stay again.