Most tournaments are held at Family Fun Arcade in Granada Hills, CA.  The address is:

Family Fun Arcade
10363 Balboa Blvd.
Granada Hills, CA 91344

Directions: Google Maps

Hours:
Sunday-Thursday: 10AM-2AM
Friday & Saturday: 10AM-4AM (Summer Hours)

Phone: (818) 360-0419 

Sometimes, tournaments are held at Interface Gamer's Network.

Interface Gamer's Network
3885 Cochran St. E
Simi Valley, CA 93063

Hours:
All Days: 10AM-12AM (Midnight)

Phone: (805) 526-9379 (LAN-WERX)