Ooh, this is MY kind of post (as a SF resident and foodie)!
Slanted Door is fun for groups because it offers sort of family style portions but it gets REALLY loud because it is so big and always, always crowded. SF is a total reservation town so you definitely want to book now.
I love Foreign Cinema for guests--it's a cool place in the happening Mission area with options for outdoor seating and a great, fresh and seasonal menu.
If you're up for raw fish (but not sushi), I LOVE Bar Crudo.
Another place that is always a hit and just off the radar enough so that you can usually get a ressie without a problem is The House. It's a tiny little spot in North Beach that does Asian fusion, emphasizing fresh seafood, with the best of them. Never disappoints!
Others that are adored (by me and Yelpers) and potentially worth a look--these should all be on opentable.com: Dosa on Fillmore (south Indian food in an upscale setting; great for sharing plates); Absinthe; Maverick (small, cute spot in the Mission with great soul/southern food); A16 (a beloved Italian joint in the Marina that just reopened after a redecorating hiatus so you MIGHT actually be able to snag a table); Bar Tartine (a longstanding Mission fave featuring fresh ingredients and a daily changing menu)
Or if you have a specific neighborhood and/or cuisine in mind, let me know!