I am sorry you missed Portugal, especially if there was a specific reason you wanted to see it.
My personal opinion is that it is not an outstanding experience. I have been to Lisbon quite a few times, including spending almost 10 days there one time when I worked for HAL and we had the Staendam in dry dock there.
I just don't feel the country has that much to offer that cannot be outdone by Spain. I hope you get to see it someday, but I would not feel too sad in the long run thinking you missed something extraordinary.