There's at least two groups on facebook that have regular gatherings:
San Diego Cosplay Association: https://www.facebook.com/groups/327947021116/
Con Artists: https://www.facebook.com/groups/192842237456031/
We also have an anime con that happens here in San Diego- Anime Conji: http://www.animeconji.org/
last but not least, there's an SD thread
Nice to meet you!