I now have an answer to the question about the best Happy Hour in the city: Hog Island Oyster Company, Ferry Building.
I had no idea that we were walking into Happy Hour as we took a couple of friends to have oysters last night.
$1 sweetwater oysters, $2 beers. It was excellent. I am not sure if they change which oysters they offer, but last night it was sweetwaters. We had: 3 dozen oysters, 5 beers, 1 bowl of clam chowder, and J had a glass of white wine. Walked out of the restaurant paying less than $60 (before tip).
It was a great time, at a fantastic value.
Happy Hours are MONDAYS only. Not sure of the specific time. I think we went around 5.30, and the happy hour definitely lasted until their closing time (7 or 7.30 I think - dependent on how busy they are lately).