I just spent 11 nights in Lisbon, 6 planned, and 5 extended because of a cacelled flight. I had such a great time and I know this tends to be a question forum but I must wanted to list a few things here in case they are useful to anyone.
Because I was there for a while I learned to use the zapper transport card that works on all publick transport: trams, buses, ferries etc. That is usful to have but the big tip I wat to give is... check out Uber. The Uber prices are so low. There were 2 of us so a zapper journey costs about 3 euros in total. But that is what the average Uber short hop cost too. It was really astonishing to us how cheap uber was and how quick the pickup was too, we hardly waited more than a minute or 3.
We did a trip too Sintra. I didn't want to be tied to the times of a tour. I was going to get a train and the time shown from door to door using Google maps / transport was 90 minutes. Uber was 30 minutes and the cost... from Lisbon to Sintra.. 20 euros each way. I means seriouusly this is amazing. We went to Pena Palace, Quinta de Regaleira, Monserrate Palace and Sintra town in our own pace. Our entire Uber cost for te day was 66 euros. With the above places Pena Palace was my least favoutire. Regalerira and Monseratte were superb and the gardens at Monseratte were so lovely, far nicer than when I visited in the summer a couple of years ago.
As for tours, I went on 4. There is one that stood out and I think t is really worth mentioning here as they are not that visible online. I found the tour on Airbnb but it is always better to approach people directly to avoid a slice of their profits being taken by a 3rd party. It was a 3 hour walk that followed the old water system in the city. So we started at a fountain and traced the system back to the huge 'cathedral' cistern and the big aquaduct. The tours are run by a couple and ths was conduced by Anabela who was very knowledgable and extremely friendly and interesting. You can find them at: https://pleasure2invite.com/ They aso put longer itineraries together.
I had great meals at: Zapata The grilled prawns were spectacular, I had them on 3 separate evenings.
Most Fado restaurants are tourist traps but A Baiuca Fado was great, reommended by a guide and she was spot on, it's small, like 20 people max, and most of the staff have a turn singing as well as fado singers to come in for the night. There is s minimum psemnd of 25 euros for the evening and the main courses cost 17 euros and were very tasty. To book you must phone.
The Gulbenkian Museum is a real gem with an extensive collection and what struck me was how everything in the museum was of such exceptional quality. It had me WOWING right from the ancient Greek coins right through to Lalique jewlery. If you like museum, this one is unmissable.
Hope the above helps someone. Any questions just ask :)