Everywhere is fine for a solo diner - sounds like European, meat, chicken, and pork
hayes valley has RT chicken, rich table, suppenkuche, jardiniere, souvla, petit Crenn, absinthe, Dobbs ferry, Hayes St grill, Stacks, Zuni, 20th century, paxtis pizza, and Chez Maman ...
plus it's flat
also salt & straw, la Boulangerie, Johnny doughnuts, Hayes bakeworks, and smitten for dessert
plus Flight001 if you need anything for the airport