On a recent visit to San Francisco, a friend and I took Grace Ann Walden's North Beach food tour. Summary: I wouldn't do it again or take any of her other tours. Two of the places we were supposed to visit were closed, including the one I had most anticipated, the focaccia bakery. That may not have been her fault, but there was no compensation or alternative stop. I didn't think to research her tours on Chowhound until after the fact, but when I did I found a comment from 2000 to the effect that she always shows up late, and she did. We found her to be somewhat abrasive and highly self impressed. I would advise anyone else considering a visit to North Beach to skip the $60 fee and wander around yourself. The area is not that big; you can see all the shops and I'm pretty sure they would be happy to give you a free taste. (And don't miss the handsome and charming chocolate truffle maker!)
The tour included lunch at Washington Square Bar and Grill, which was fine, as discussed below under the Washbag post.
Incidentally, I took Shirley Fong-Torres' walking tour of Chinatown years ago and found that to be much more worthwhile.