California Grill is absolutely louder than AP or Jiko.
However...
The food quality at Jiko & AP is just not there. Artist Point has a delicious portabello mushroom soup, but everything else we've ever eaten there was just so-so. And we've tried it many times, with a wide variety of dishes.
Jiko isn't even in the same class. This is a place where, at one of their signature wine dinners, they served BACON and a chicken-stock based soup to us, after we had explicitly spoken with them about our dietary preferences and had informed them that we eat no meat and had been assured that they could and would accommodate us. That inattention is sloppy and what I would be irritated at in a TGI Friday's, much less a signature restaurant. The foods that we've eaten there have been fine, but nothing outstanding.
It's really the sushi at CA Grill that sets it apart. If you are a sushi fan, you will be delighted at this restaurant. Admittedly, the signature restaurants continue to cut back on the quality & standardize the menus, but, at least as of August, CA Grill was still the top signature restaurant.
Yachtsman doesn't have the quality that it used to have. It's sloppily run, and offered us very low quality ingredients. Blech...
I would recommend CA Grill; we have 2 reservations there for our next on-property stay, since we were so disappointed with the other signature restaurants we dined at this January & March.
Cheers!
Heather W