On this sunny, 55-degree Tuesday in March it feels like the whole of Seattle is on vacation. There are moms with strollers and hot dog vendors and gaggles of teenagers crowded along the city’s waterfront. I hear seagulls in the distance, that faint soundtrack of voices and birds and cars inching past looking for parking — but I don’t see them. I keep walking, past the aquarium, some souvenir shops, and finally a candy store, before arriving at last at Pier 54. The gulls, I discover, have found the best place on the waterfront to converge: the seafood bar outside Ivar’s Acres of Clams