Boston: I like Neptune on Salem St. in the North End. Have had good
oysters many places from Legal to McCormick to Union.

NYC: Another vote for the O-bar at Grand Central, though I haven't
been there in a while.

Washington: haven't found one, though I seem to recall some
pretty good oysters at the various Clyde's places (Tower Oaks,
Old Ebbitt Grill, etc.).