My hotel was near Lake Union and the path near the lake was perfect for early morning walks. I also explored the Center for Wooden Boats which is located on the lake. I would have gone to the Museum of History and Industry, but ran out of time.
The Center for Wooden Boats is like a museum for boats, but they also believe in teaching through direct experience which I think is pretty awesome. They offer boat rentals – sailboat, canoe, rowboats, and pedal boats – by the hour. If I lived in the area I would love to take woodworking, sailing, and boat making classes. They also offer free boat rides on Sundays. Viewing the boats along the docks at Lake Union was a perfect rainy morning excursion.
Next Exit Travel 
When I was a boy, growing up in Richmond Hill (Borough of Queens, NYC), an uncle of one of my friends, who lived around the corner, built his own (about) 14ft. wooden motorboat from scratch. All the kids in the neighborhood would stop by when they were passing the yard to see the progress.