I know it is a tourist destination, but if you haven't strolled around Pike Place before it is definitely worth a visit. Pro tip: El Borracho has amazing carnitas tacos.
Downtown Fremont is an interesting place to check out, including the troll that lives under the Fremont Bridge.
Pioneer Square is the good place to see old Seattle. They also offer underground tours were you get to learn about the history of Seattle and walk beneath the streets.
Edmonds is a beautiful city. Main st and 5th marks the center of downtown with its little shops. Take Main down to the water to enjoy the beach and watch the ferries come in and out of port.
An adorable outdoor shopping center with a pond, chickens and ducks running around, and eclectic statues.
Snohomish is a bit out of the way but if you are big into antiques there are a large number of shops along 1st street as well as some delicious pie and the Snohomish Pie Company.