THX in the cinema is almost dead. There are only 7 THX cinemas in all of Los Angeles (including Orange County and the valley)!
http://www.thx.com/consumer/movies/find-a-thx-certified-cinema/?type=cinema&address=Burbank%2C+CA+91505%2C+USA&distance=50&pg=2
That doesn't mean there aren't a lot...