I believe the only official dress code rule there is no tank tops. Beyond that, like catheren said, you'll see the whole range. Personally, if I'm spending that much cash, and it's not in a park, I like to dress up a bit (not an evening gown or anything, but a casual dress & cardigan or some such). As always, YMMV.
Just called to make PS for the California Grill this morning. They told me that men need to wear shirts with collars (and of course, no tank tops--although I haven't seen too many tank tops with collars anyway).
What you were told isn't exactly true. They SUGGEST a shirt w/collar. But by no means is it a requirement. We ate there 2 weeks ago--in our regular "theme park casual" attire (walking shorts, Disney T-shirts, tennis shoes). There were a # of others just like us that night
As noted, you'll see all manner of dress at the California Grill. Just wear whatever you feel most comfortable in, and you'll be just fine!!
I can also attest to the truth in the tank tops allowed. My Dh was in a tank and we were going to be seated when he noticed he was the only one wearing one. He was too uncomfortable so we chose to leave. The CM tried to make him feel comfortable but it just wasn't worth it. I guess we will try back another time.