I just went to R&G and it is loud, bright, and noise, so I'd avoid that. I would try Belden: B44 and Plouf are faves. Perbacco is also a new regional Italian spot. I tried their aps, wine, and pasta dishes at the bar with a friend and all were delicious. Can't vouch for the entrees though.
A little alley up the street is called Beldon Place that has a number of little restaurants..
Lots of people like Cafe Bastile, B44 or Plouf for mussels. If you walk to the end of Beldon it will put you on Bush where Sam's is located. Old time San Francisco food which is easier to get in than nearby Tadich on California. If you go to either the sand dabs are recommended. Tadich get the cioppino. However it is louder than Sam's, takes no reservations and there's usually a line.
Very quiet is Silks in the Mandarin Oriental on California
Jeaunty at Jacks is up the street in the Chinatown direction. French with the tomato soup recomended.
Haven't been to Macaroni in a long time, but anearby Italian option.
Rubicon has a good wine list and good food and a nice atmosphere
Louie's can be average unless you know what to order. Work with your waiter, if possible. There's a new chef there I hear and I don't think anyone has reported recently.
Hope you will report back on where you ate.
We're in the middle of Chinese New Year celebrations. Given that it's the weekend, I'd expect popular spots like R&G Lounge and Great Eastern to be slammed and noisier and more crowded than usual, so probably not a good pick given your requirements. You'll find many posts on both by searching. If you persist, call for a reservation and you may be able to judge by the stress level in the receptionist's voice and background noise...