I think Lisbon's Barrio Alto is a special area - there is a very artsy, laid back vibe with great little cafes and bars. Stuff tends to kick off quite late (many shops don't even open until midday) and the area really starts to come alive around 8pm.
http://travelinsider.qantas.com.au/lisbon_the_high_life.htm almost 10 years ago
Personally I love Monsanto, it is known as the lungs of Lisbon it is the great big reservation area just behind the centre of the city.
Barrio Alto is great too, although it is a bit touristy in summer and tends to be a big attraction for pick pockets.
Graça is a great area to find fantastic lookouts behind the São Jorge Castle (which is also a great highlight) almost 10 years ago
I recomend you a cruise on the river Tejo. See the web page www.lvt.pt the boarding is mear the torre de Belém.
A night life is on Bairro Alto. And visite also Parque das Nações (Expo 98 area), specially the Oceanário, the biggest aquarium in europeia. Have a nice time! about 8 years ago
By day walk around avenida liberdade, rossio and baixa areas passing by terreiro do paço the walk towards Sé and são Jorge castle but make a turn to visit panteão nacional. By night go to bairro alto
go to Belém and visit mosteiro jeronimos, padrão dos descobrimentos, free Expo in CDB, walk by the river and eat pasteis belem. Dinner by the river
go to Guincho, Cascais and Estoril.around Casino estoril área by night offers good food and fun. Several beaches in the area
Spend a day in Sintra.
Dont miss 1/2 day in Caparica beaches about 8 years ago