Regardless of what you choose to do, be sure you have rain gear - at least an umbrella - and good walking shoes. Seattle is built on hills and some are rather steep. I recommend taking a wardrobe that you can layer. It can be cool and damp in the morning, warm midday, then cool and damp late afternoon and evening. It would be a rare day not to have grey skies and a mist most of the day. The home of Starbucks, Seattle is a coffee-over's heaven. Most of the time the smell of coffee overpowers the salt/fish smell of Puget Sound. If you like lighthouses there are many to see.