I will be staying with American friends who live near Oseiras in March. They have done a lot in Portugal and beyond, but are open to my requests or suggestions. Thanks!
Do you have a copy of RS Lisbon Guide Book yet? If so, good. If not, you should get one. It has lots of information for you. You might also want to get a RS Portugal Guide Book for even more information. We use these when we traveled thru Spain and Portugal. You can order either or both elsewhere on this web site under "Books".
In Lisbon - the Port Institute, wandering the Alfalma and all of Lisjon, Sintra, Cascais, Sintra, maybe out to the Alejento Region and visit Evora, Estremoz, and Monsaraz. In Lisbon eat at Sacramento. Shop at La Vida Portugal. http://www.avidaportuguesa.com/
I'd highly recommend Sintra!
In Lisbon: check out the Gulbenkian Museum. Excellent. You can read about it in RS.
Totally agree with Charlie; Rick's book had excellent advice/suggestions on areas to visit. Pick up as copy and do some reading.
The port tasting room at the top of the funicular (forget which one this is but the guidebooks will say). Pastis at the bakery in Belem. The watchtower at Belem. Eating roast chicken with vinho verde at one of the dualing chicken joints just off the main restaurant row. The ruins of the abbey overlooking the city. These are a few of my favorite things...