Guided tours

Rick Steves has an organized tour of what he considers the highlights of Portugal (which includes most of the major sites, except the Algarve).

You could also hire your own guide through Tours by Locals.

Rick Steves recommendations

If you want to stay in the sunny south — the Algarve —and you want to avoid the more touristy town, try Salema. A good mixture of locals, so you can watch the fisherman getting their boats ready on the beach before heading out for the day. There is an excellent beach with mostly locals relaxing.

Rick has a extensive resources about Portugal on his website.

He recommends the A Maré (The Maré), Praia de Salema 8650-194 Budens, as a reliable place to stay.

Videos

Rick Steves has a few good videos on travelling in Portugal.

Lisbon and the Algarve

Portugal's Heartland

Lisbon

Rick's extended presentation called Portugal Travel Skills

Portugal with Rich Earl (who works for Rick Steves organization)

Starting out

Looking into all things Portugal.

Portugal has so much to offer:
The sunny south of the Algarve with vast beaches.
The old sections of cities like Lisbon, Évora, Nazaré, Fátima, Óbidos, and Porto.
Port production is centred in Porto. The Douro River flows to Porto, and the Douro Valley is spectacular.
The wine country is also nice place to visit. Wines are grown throughout Portugal, but the popular Vinho Verde is grown in a large area just north of Porto. Lots of vineyards (called Quintas) are open for tourists and let you sample their wines. Here is a list of some popular ones (according to the website).

Lisbon - the spectacular mosaics on the walls of the São Roque Church & Museum that are so finely made that they look like paintings.

Nazaré - Old ladies walk the streets with signs advertising rooms for rent. They are usually very good and inexpensive. Fisherman still bring back fish that are dried in the sun. A local treat is freshly harvested barnacles! Apparently, delicious.

Óbidos is a univeristy town with lots of history. See their tourist guide.

Alcobaça - see the Alcobaça Monastery

Batalha - see the amazing Moorish influenced Batalha Monastery (Mosteiro da Batalha)

Santiago de Compostela is the terminus of the famous Camino de Santiago pilgrimage.

Fátima is the famous Catholic shrine of the Santuary of Our Lady of Fátima, visited by about 5 million people per year.

I'll check out a Libertarian group in Lisbon.

This website has many excellent articles about sites and tours all around portugal.