From the Left Coast Crime bylaws:
The Left Coast Crime Convention is an annual event sponsored by fans of mystery literature for fans of mystery literature, including both readers and authors. Usually held in the western half of North America, LCC’s intent is to provide an event where mystery fans can gather in convivial surroundings to pursue their mutual interests.
There is always a Guest (or Guests) of Honor, and always a Fan Guest of Honor. In recent years, the Guests of Honor have been mystery authors, one male and one female. This year, they are John Lescroart and Jacqueline Winspear.
This year will be my fourth Left Coast Crime. I had such fun on the Planning Committee in 2010 that I offered to help this year, too. Somehow, I've ended up as Co-chair of Programming, which is turning out to be as much work (and as much fun!) as I expected.
If you've never been to a mystery convention before, Left Coast Crime is the one to start with. The average attendance is usually less than 500 people, so it's not as overwhelming as a large convention such as Bouchercon, which I understand can be as large as 2,000 registrants.