One of the best times to take photos from a cruise boat is when its leaving port. That would go double in Seattle. (please see below for more text and second photo)
I shot these photos several years ago on a cruise that left Seattle late in the afternoon. The clouds were quite dramatic. One really gets a whole new perspective on things when you are standing several stories over the water, especially in Seattle, where you have the mountains on one side of the boat and the city on the other and several boats in the water below.