One of the anchor restaurants on Beach Drive, Cassis does a reliable French-American brasserie menu with an emphasis on Florida seafood. The oyster selection is good, the mussels are done in the classic style, and the fish changes with the market. The sidewalk terrace is the draw when the weather cooperates — which in St. Petersburg is most of the year.
Not the cheapest option downtown, but consistently well-executed. Reservations are recommended on weekends.