The question about shows in the Los Angeles area came up last week in another thread.
I'm in the Los Angeles area.
The two largest shows each year are:
- OrcoExpo (coming up soon, Jan 15-17, 2017) in Fullerton
- SESCAL (Oct 13-15, 2017), in a new location this time, Ontario Convention Center.
OrcoExpo has a very good selection of dealers, but is primarily a bourse (dealers). http://www.stampshows.com/fullerton_sp.html
SESCAL is a full-blown APS World Series of Philately show, with exhibits, stamp society meetings, etc.http://www.sescal.org/
SESCAL has been out by LAX for many years, but, in my opinion, the most-recent show hotel has not been great, and people and dealers have become increasingly dissatisfied with the location. The change to Ontario might help a lot. (For instance, I should be able to volunteer now, whereas the drive-time to the other location prohibited that. (30 min now vs 90 min before, even though they're both about the same distance from me.))
There are also several monthly bourses around the area, in Glendale, Van Nuys, Arcadia and Anaheim. (I hope I'm not forgetting any.) If you're looking for more info, and can't find it easily online, feel free to contact me if you'd like.