In July of 2014, I visited the city of Tomar, Portugal. It wasnt mentioned in Rick
s 2012 Portugal guidebook. We stayed 1 night, but wish we had 2 nights. There is a great castle ruin there from the time of the Crusades. We happened across a free concert in the old convent. The acoustics were wonderful. The oldest synagogue in Portugal is there as well. Google it for more information. If you do go, I highly recommend renting the services of Tuk Love. It is a tiny little vehicle that easily goes down the narrow streets. You will see a lot in a few hours. It was very hot when we were there, and this was just a wonderful way to see this small city less than 2 hours from Lisbon. Not many tourists there. Americans have not discovered the beauty of Portugal yet. Go now, before they do.
I agree with your assessment - Tomar is an undiscovered gem (at least, undiscovered by Americans).
I was in Portugal in 2002 and saw Tomar as a day trip from Santarem. I enjoyed both cities. In addition to everything you mentioned, Tomar has the museum of matchbooks, which was fascinating (wait till you see the Nazi Party one!).
Santarem and Tomar are on the same train line from Lisbon (Santarem is one hour from Lisbon, and Tomar is an hour further from Santarem).