Two good French places near the Pike Market - Le Pichet (as close to a real French bistro as you're likely to see) and Campagne, a great place with great food.
Two seafood places, tried but true - Elliott's Oyster House, right in the middle of tourist hell on the central waterfront, but great despite the location, and Anthony's Pier 66 places, $$ upstairs, $ down.
Tom Douglas' places - Dahlia, Etta's, Palace - are quite good but IMO awfully noisy and taken with themselves. Our favorite downtown Italian place sadly is closed on Sundays - Assagio. Still, the Pink Door in the Market (off Post Alley - no sign, just a Pink Door) is very romantic and cozy in the winter (fab in summer on their roof deck, but not in Feb.)
Metropolitan Grill and El Gaucho for $$$teaks - bring your banker and a flashlight to El Gaucho.
What's your hotel?