Annual Tri-Star San Francisco Show
For the past several years I've been going to this show. It is well worth the 1 1/2 hour drive from where I live. I usually go on Friday because on the weekends they usually have a stellar lineup of autograph signers which draws in larger crowds.
Many dealers focus on the local teams which is good if you are looking for cards of 49ers, SF Giants, A's, Warriors or Raiders. It's probably the best show that I've been to in Northern California. If you enjoy getting autographs, they generally have a good lineup of signers that in recent years has included Buster Posey and Madison Bumgarner.