As you probably already know, CYM (California Yacht Marina) and CVM (Chula Vista Marina) are both in Chula Vista Harbor. When I was looking for a slip, I found CYM to be a bit cheaper and could see no reason to prefer CVM over CYM. I haven't compared their rates lately. Maybe with the last two increases, CYM has caught up to CVM.
With its proximity to the Galley restaurant, CVM can get a bit noisy on the nights when the Galley has live entertainment.
Additionally, with CYM you get to join the yacht club at no cost. The yacht club dues are subtracted from the slip rent.
Also, as Jeff pointed out, you get reciprocity with other CYM marinas and other yacht clubs.
I know that this may sound like an ad for CYM, but I have absolutely nothing to gain should you choose one over the other.
Charles