Well theres the many cosplay gatherings happening every day. Be sure to check the gathering list to see when your favorite fandom will have a gathering so you don't miss photo opportunities. See if a pannel your interested in is going to happen. Check the schedule as soon as it's out. Most pannels are different every year so I can't tell you any specific ones to see. Check out the dealers hall and artist alley, see if anyone has something you like on sale. And the most fun activity, ribbion hunting. You will see people walking around with these ribbions hanging off their badges. You need to do something special for the each person handing out each unique ribbion. There's a lot, and I can't tell you how to get most of them cuz I've never had them, but I can tell you one. You can get the "My first time" ribbion at the information booth by telling them it's your first time at the con. The rest I leave to you to earn on your own.
Anime California plans
Pricilla (Fire Emblem Rekka no Ken) - 10%
Dr. Francis Stein (genderbent Stein from Soul Eater) - 0%
Liza (Pokemon R/S/E) - 100%
2014 Cons: Anime California, Comikaze (maybe), Bent Con (maybe), Nuke the Fridge con.