one more day.. of course.. there is so much to see..the beaches area Estoril,
you could go to Fatima ( if you like religious adventures)..very interesting even for those of us who are not Catholic.
The Algarve.. heck you could spend ages there and not see everything. We have ben there at least 6 times and we sure haven't seen it all.
A must..
One evening you should catch a fado show( this is the singing style of the region)there are many great restaurants that have it.. I was checking on the guide site I gave you above.. and they will assist you with reserving at one they recommend or take you there..look on that site under FADO..