I really enjoyed staying at Andreia's place!
You can reach everything you need (supermarket, metro, restaurants, cafés) within a few minutes.
Andreia even made it possible for me to checkin earlier than normal, she's such a sweetheart. If you're a light sleeper I'd recommend you to bring some ear plugs because its kind of a busy street (traffic wise). It really depends on the season I think. I'll definitely come back some day.
If you wanna spend a day at the beach you can take a train from the train station Cais do Sodré to Cascais it takes about 40 min and the beaches are stunning.
And I'd also recommend visiting Sintra it's such a beautiful city!