Have you been to Lisbon before? If not, 3 nights (i.e. 2 days) isn’t enough if one day is going to be a day trip to Sintra.
Obidos is worth a couple of hours, but I wouldn’t stay there, particularly if you are going to use it as a base to see Alcobaca and Nazare which are both to the north before driving north to Coimbra. Why head back south to stay? Personally, I think Nazare is over rated but Tomar, Alcobaca and Batalha are all worth a visit and I would stay in this area, not Obidos.
Your time in the Douro is rushed with the side visits you have planned. Many of the roads are winding and progress can be slow.
Porto is compact and could be seen in a full day.
Unless you are prepared to add another week, you don’t have time for the Algarve. Salema has been ruined by over development and has lost its character, so wouldn’t be my choice of where to stay. If you want beach time, add some days around the Silver Coast, which would be less driving.
Portugal is a beautiful country, but unless you want to drive on the boring motorways and see little, driving is slow and time consuming.