I am so upset I will be out of town for the Pet Fair in Marin this year! I went last year with my little baby and it was a BLAST!! They put on dog shows and have lots of adoption groups there and all sorts of different types of animal booths! I live in Marin and frequent the SF Yorkie Meet up in the Marina. I know they are typically on the first Sunday of every month and are a BLAST! The dogs have such a great time! I'm not sure which meet up you were asking about, but you can check out the SF Meet up at:
The San Francisco Yorkshire Terrier Meetup Group (San Francisco, CA) - Meetup.com