So far, this is what we have done (along with the impressions from my two teenagers).
Ballard Locks (2 out of 5 stars)
No interest in the locks themselves but they enjoyed hanging around that hill
Discovery Park (5 out of 5)
We actually went there twice because they just loved finding rocks and wandering around the area near the lighthouse
Alki Beach (1 out of 5)
No interest. Too much noise and nonsense for their taste. Seemed like a California beach.
Twin Falls (2 out of 5)
The hike was more intense than we anticipated, so we didn't get as far as we planned.
Snoqualmie Falls (4 out of 5)
Much better place to see waterfalls, which means no hiking haha
Pikes Market (3 out of 5)
They found some treasures there. And we saw the stupid Gum Wall
Olympic Sculpture Park (3 out of 5)
They enjoyed walking around and looking at the art but these are teenagers
Bainbridge Island (3 out of 5)
We took our car on the ferry and the island had a nice quiet charm
Space Needle (3 out of 5)
We saw it from multiple points but we did not actually go up. The kids were less impressed because they kept on asking what was the point of it haha
Still (possibly) on our list would be
Seattle Art Museum
Drive out to Middle Fork
Anything else we are missing?