I'm just starting my research on Portugal now, but for an 8-10 day trip we're thinking about being in or near Lisbon to see Lisbon, Sintra, Obidos, and Tomar, then moving to the Algarve coast, and then a stay in Evora before returning to Lisbon to fly home. That leaves out the northern wine country but my wife is not a fan of port wine anyway.
When we travel, my wife and I prefer to avoid the larger cities when it works. It seems that many visitors to Portugal stay in Lisbon and take day trips from there to Sintra, Obidos, Tomar, even as far as Evora. Assuming the use of a car, would the reverse work? Could one easily stay in Obidos, for example, and day trip to Tomar, Sintra, and Lisbon? Would that even make sense? As an example, when we visited Nice, France we actually stayed in a town called Villefranche-sur-mer out of the bustle of Nice and just took a day trip to Nice, itself.