Big Four, The - An elegant, formal restaurant in the top-notch formal Huntington Hotel atop Nob Hill. If the Tadich Grill is rough-and-tumble old San Francisco, this is railroad robber baron old San Francisco. Great polished wood paneling, formal service, good wine list. Get your meat and potatoes (with truffle oil) here. Extra credit to anyone who knows "The Big Four". Recommended.
Biscuits and Blues - Blues club in a basement near Union Square. There are some great blues acts booked here. If you simply need to hear Lavay Smith and Her Red Hot Skillet Lickers (and if you haven't heard them already, you need to do so), there are few choices. The food is barely edible. Stick to drinks. Not recommended (for the food).
Bistro Clovis - French Bistro near the Civic Center and Performing Arts centers. Very French decoration, and a very French menu. I had the Duck Confit and had no complaints. I've never been back, so I wasn't overwhelmed, but it has potential, and I need to revist. No recommendation.
Bizou - Bizou is a bistro, but it isn't French. It is French/Cal/Italian/Spanish. It is constantly exploring interesting tastes and textures using classic French technique. It has been in SoMa for ten years, and part of the professional and friendly staff has been there almost the entire time. The menu changes constantly reflecting seasonal produce. I think the appetizers are better than the entrees, but you can't go wrong here. Highly recommended.