I'm in San Francisco about 2-3 times per month, for a night or two each time (I live in SoCal). My normal 'regulars' when not entertaining clients is lunch at Swan (love the place) and dinner (whenever possible) at La Folie... I think it's the best French food in SFO, very possibly in Calif... but that's just my opinion.
I'm also fairly fond of Masa and Aqua, I've had very "solo dining friendly" experiences there. I usually stay in a hotel right near/around Union Square. But tonight I'm going to check out Hama-Ko... I LOVE traditional Omakase style sushi. Good idea or bad?
Any other recommendations? Just got back from the Masters down in Carmel, and had great food from Gras of 5th Floor and Dangko, so they are definitely on my list... any other places? Ethnic places that are EXCELLENT and walking distance from Union Square would be great! Also, as I eat alone quite a bit, if any local 'hounds want together for dinner some night, just email me.
The downside is that many times I'm saddled with meals with clients/partners, etc... so I can't select the places I would normally choose, so I eat more mediocre (but expensive) food with business folks than I'd like.