Kevin and I are also Sushi nuts. We have sushi and sashimi at least once a week. We're also EXTREMELY adventerous eaters and will try any and all creations offered to us by Sushi Chefs.
Having said that...California Grill will probably be a total disappointment for you in the sushi department, although it is better than a few places I've been to.
We tried CG on our Easter 2005 trip. We sat at the sushi counter and although the fish was fresh, CG had nothing except for the generic ordinary items. Tuna, Salmon, and the like. Rolls were pretty unadventerous also.
They do have sushi choices as a meal, and not just appetizers.
We started with a "Snake in the Grass" roll and some sashimi.
And followed up with CG's version of a sampler platter.
We've also eaten at Wolfgang Puck's Sushi counter and felt pretty much the same. Very fresh seafood, but unadventerous to our tastes.
Blue Zoo, we've heard mixed reviews on, but have not tried it ourselves.
I think if you keep in mind that Disney's version of sushi caters to the "masses", you'll find very fresh offerings, although very generic.
Let us know what you find on your trip!