Inside the city,the possibilities are:
-Pike Place Market
-Waterfront on Alaskan way
-W Seattle/Alki Beach for city skyline view or night view
-Kerry Park and Magonolia Bluff for sunset and night views of the city
-Gasworks park for city view and Lake Union
-Take the car/passenger ferry to Bremerton or Bainbrdge Island or Kingston and time your return ferry for sunset
-Boeing Factory tour N of Seattle in Everrett, only on weekdays (not the museum in S Seattle
-Ballard Lock to watch salmon over the lock and boats passing the lock
-Lake Washington Argosy boat tours (if you like to see the multi-million mansions, including the Gates house)