And, if you head to West Seattle (where Alki is located) you can capture some city skyline shots looking East across Puge Sound. It is a wide photo to capture from the Space Needle to Safeco Field. Drive along Harbor Ave. SW off the West Seattle Freeway/Bridge.
Discovery Park lighthouse is another great area along a very rugged beach. It is a long hike over a fairly difficult trail, down to the beach. This is in the Magnolia area of Seattle
If you want some wildlife photography, Juanita Bay Park Wetlands (not Juanita Beach) on the Eastside in Kirkland is full of water fowl who have made the wetlands home for the winter. Many water fowl species have migrated South from Canada and are not seen here during spring and summer. Lots of Bufflehead, Green-winged Teal, Mergansers, Heron, Eagles, Wood Ducks, and others.