What are the best spots to celebrate Oktoberfest in San Francisco?

Suppenküche in Hayes Valley is where you'll find me on most years on the first day of Oktoberfest :)  I go at noon'ish towards opening otherwise they get very crowded.  It's traditional German beer hall style, so you'll be sharing communal tables and benches with others.  Very festive! 

I always get a half liter of beer (my more gluttonous friends can chug down several litters).  Sometimes I get their traditional beer cocktail-esque drink, like a wheat beer with banana juice.  I also have to get their giant bretzel with two globs of bavarian cheese dip to share.  My friends and I usually order one of everything on the food menu.  Typically 5-6 dishes.  

A sampling of their food:

Me with said pretzel:

Their nearby sister spot Biergarten is also pretty awesome, especially the patio if it's not raining (it was raining cats and dogs on the first day of Oktoberfest last year though!).  Solid beer list, of course.

If you want to go to an actual festival, there's Oktoberfest by the Bay at Pier 48.  You buy a ticket, get a glass and some drink tickets and you can go around trying different biers.  Some people get all dressed up for it:

Prost!

Pier 48 along the wharf has a Munchen style celebration (Oktoberfest by the Bay); bands/food and of course beer.  Loads of fun, and although has tourists, plenty of locals mixed in to join the great venue. 

Suppenküche or Biergarten - Hayes Valley

Nature Friends San Francisco Tourist Club Hike in Mill Valley - this is a pretty hike that leads you to a beer garden. Great place to bring a picnic and hangout with friends for the day. It's not open to the public every weekend so check the website before going. Not sure if they will be open during oktoberfest!

Oktoberfest by the Bay