There are some excellent restaurants in and around the marina.  Try Rui's Bar and Carvery in the square just behind the marina if you want English fare.  If you want traditional food there are loads of places serving fresh sardines and other fish dishes.  Try Ostra D'oura opposite the steak house, and also the Mayflower on the marina serves excellent Salmon, Sea Bass and steaks.  Some other restaurants to consider: Il Lamparo (international cusine),  Zu Yi (Chinese), La Fragata (Italian), Akwavit (Swedish), and Pier One (fusion,international). The casino in Vilamoura also has a restuarant and cabaret bar, they serve a 4 course meal with wine included for about 27 euros, this includes the cabaret.

 marina at night