Cape Disappointment and Fort Clatsop were easily among the highlights of our summer trip. There's a wonderful Lewis & Clark Interpretive Center out at Cape Disappointment. This particular Interpretive Center focuses on activities of the Corps of Discovery on the coast, so it's not a case of "you've seen one center, you've seen them all." Right next to the Center, almost attached to it, is another old Fort, but from far more recent years than the early 1800s! Worth a walk through. Please note that the walk from the parking lot for the Cape is up a hill, but it's short. You also have to pay two fees. One is to Cape Disappointment State Park, then a separate fee for the Center, but neither were unreasonable.
Fort Clatsop is separate from Cape Disappointment and involves a re-created Fort which reminded us of Fort Mandan (ND), but was different. You can also hike out to the boat launch area that they believe the Corps used.
As for Olympic, because of the fires, we enjoyed the Staircase region, but we also enjoyed Ruby Beach a lot. I think we were on that beach for an hour or so before moving on to Kalaloch, where we spent another half hour or hour. We were going counter-clockwise on US-101, so that the beaches (when we got there) would be on our right hand side.
Are you a fan of the book/movie series Twilight? If so, check out Forks. While the movies were not filmed there, you can check out several places that the author used in her series. (I never liked the movies, but read all three books and enjoyed them. My daughter was more the fan, so we sent her photos of the places we could check out, but did not go out to LaPush.)
Donna