Lots to do in San Francisco, but if you're looking for aquarium-related things, I would definitely stop by Ocean Aquarium. It's definitely the most unique LFS I've ever been in. You'll see what I mean if you go.
There's a lot of stuff to do in SF! October is the best month to go, we have an indian summer, so it doesn't get warm until september/october.
For fish stores, AFA obviously, the rest aren't really worth going out of your way for.
A perfect day would be breakfast at Brenda's in the Tenderloin, then head to the Mission for some bi-rite ice cream and hang out in dolores park. Then head out to pizza delfina for an awesome pizza for lunch, then for dinner, check out bobo's in the Marina for the best steak in the city.
I know I'm going to AFA, and china town, and fishing, but is there anything else? It'll be in October.
Are you joking? You're asking if there is anything else to do in SF other than China Town? Pardon me, but have you been under a rock?
Golden Gate, Alcatraz, Academy of Sciences (aquarium) Union Square, Fishermans Wharf, Cable Cars, Zoo, SFMOMA, and just walking around and checking things out. Jeebus, I've never been to Chicago or Boston, but I can think of half a dozen things to do in each place off the top of my head.
Nah it's a museum crossed with a zoo/aquarium I guess. It has a lot of really cool exhibits including an albino alligator. They also have a rainforest exihibit which is REALLY cool. Here is a thread of the place here Calafornia Academy of Science- Post your Pics! (56k!) There are some of Speedie's pics in there
You get lost in the giant aquarium its amazing. I went there a month or two ago and they have salt water, freshwater, biotopes, ripariums, and pretty much everything. They usually have a special exhibit too first time I went it was rollercoasters and last time it was earthquakes.