Saboia Hotel

This is a very friendly and clean hotel in a lovely central position, overlooking a little park area, close to local shops and some very nice restaurants. Quite basic, but a brilliant base to discover the area from.
It is only a short walk down to the main promenade and the little train station. Trains run between Cascais and central Lisbon (which is a must see and do).
Estoril is so historic and has some very beautiful streets with old buildings everywhere. There is also a casino that stages great shows, which you can book to go to including a meal and impressive ornamental gardens just outside the casino.
Cascais is great for an evening out, with it's quaint squares and cafes, but Lisbon really is one of the most fascinating cities that I have ever visited. It really does have everything if you know where to look. In the evening there are a wealth of bars and restaurants to visit and during the day there are castles, museums, churches, shops, squares, cafes and historic (and some very modern) features everywhere.
The other place that you just should not miss is Sintra with it's fabulous castles and exciting follies. A bus will take you there from nearby the hotel or otherwise, car hire is always handy in the area. The hotel has parking outside the main entrance.