I live in San Francisco, and most of the comments 
are correct.  There are not too many cel shops, 
but there are many small mom and pop operations 
that sell anime related goods.  I agree that 
Newtype would be a good resource.  I havn't 
visited them myself, but it sounds like a good 
place.  Japantown is a good place to recreate.  
Japan Video and Media has a good selection of 
anime titles and a decent rental section, but 
many of these can even be found on Netflix.  As 
for sightseeing, where can I begin...  There are 
many touristy sites like Alcatraz (a bit cold in 
the winter), Fishermans Wharf, Pier 39, Chinatown 
(OK chinese food, but the best restaurants are 
the neighborhood restaurants), walking around in 
North Beach (Great Italian food), Union Square 
(good for all kinds of shopping).  There are 
literally hundreds of great restaurants to 
recommend.

For more cultured pursuits, the Asian Art Museum 
is a good choice, especially after the expansion, 
move, and renovation downtown.  The Legion of 
Honor at Lincoln Park has a great view of the 
Pacific Ocean.  The MOMA (Museum of Modern Art) 
is also a good choice.  It is right across from 
the Moscone Convention center and close to the 
Sony Metreon (a large theater-shop complex).  
Many of the large science and technology 
conferences are held at Moscone.

As for cels, I would love to trade with you if 
you had the time.  My interests are primarily 
CLAMP anime, NOIR, Nadesico, and some others.  In 
fact, there was an Umi (Rayearth) cel that you 
have that I would love to trade for.

Anyway, email me if you have any specific 
interests or want more information about SF.

Craig