While in San Francisco why not do something very San Francisco... no, not go to the Golden Gate bridge. Have a lateral tasting of Anchor Christmas beers from 1998 to 2010 with a good group of about fifteen.
My brother had stored at least one magnum bottle of Anchor Brewing's Christmas Ale from 1998 to the current 2009. Supposedly the recipe for the beer changes from year to year, unlike most special Christmas ales released by other breweries (they also change the label each year as well). All are a Porter base, but the spices, and levels of spice change. So we did a tasting over twelve years with only 1999 missing (not sure where that bottle went) to find out if there was much of a difference and if any of it went bad.
The good news: none of the bottles went bad. Each opened with some fizz to it. But we all agreed that some of the flavor must have been lost over the years. As the each bottle was opened (we started with 1998) they seemed to get better and better. Yes there was a difference between the years, but not as much as we thought there would be. The biggest difference we found was between the last two (2008 & 2009). Last year's beer was so heavy and more sip-able (more of a stout), while 2009's beer is the most drinkable in a long time (less spicey, less heavy). The other issue we ran into was we all were getting so full - Anchor Christmas is quite a heavy beer, like many porters.
All in all it was a fun night with a great group of people. In the future I would do the tasting over 5 years and not more than that.