Hi
I already saw you had good advices from Filipe and Nuno. Sintra is a must.
You can go by train. But you are thinking in going by car, you can return to Lisbon passing by Cabo da Roca, Cascais, Estoril.
Inside Lisbon go to the castle, there you have a great view of the city and the river. and in the way up you are crossing a very old neighborhood - Alfama, and you also have the old Cathedral in the way up.
YOu should also see Mosteiro dos Jerónimos in Belém, and Torre de Belém. If you are in thar area don't miss the Cakes "Pastéis de Belém" in the special cake shop. YOu just have to ask there where it is.
To have dinner, Bairro ALto has plenty of choices, with plenty of prices...
There you have lots of bars also. Normally people stay in the outside talking and drinking. I don't know the kind of club you like, but the "bedroom" is a kind of club in Bairro Alto. Jamaica, and Music Box are within walking distance. After 3 am there are crowds trying to get in, so try to go a little earlier.
Lux is cool, but you have to go by cab. Any questions or doubts you can write to me, i think you can see my email?
Have a great trip to Lisbon.