Our young family had a wonderful 8 days in Ana-Ritas apartment. Its right on a wonderful little beach, where we swam and played most days, and was very convenient for trips to Lisbon and Cascais. It is also surrounded by some lovely restaurants (Mami-Wata and Paco Bigontes stood out), and a mini-market with all the basics.
The apartment itself is very comfortable and was a relaxing space to come back to after a day seeing the many sights around Lisbon.