I spent wonderful weekend at Diogo apartment in Alfama. Diogo was very hospitable, his apartment was clean, big, modern and cosy, and the area where his apartment is situated was perfect for me, it is center but at the same time there not so tourist-crowded places (like Esquina do Fado) where you can eat and listen waiters singigng songs) . It is the district that is usually on the pictures of Lisboa, where it is easy to get lost without a map!
Diogo is very flexible about arrival time (that was the reason why I chose his apartment), and I don't regret about it!=)