Consider Anacortes or perhaps even La Conner. It puts all of Whidbey Island within reach (Rosario Beach, Deception Pass, Fort Ebey State Park, Ebey's Landing) but you could also do day trip drives up Chuckanut to Fairhaven and Bellingham. Good hiking in and around Larrabee State Park and Samish: Oyster Dome, Lizard and Lily Lakes, Fragrance Lake, Pine and Cedar Lake. I believe there is a fair amount of mountain biking around Blanchard Mountain, too.