I've taken the the sushi and sashimi classes at Sur La Table.
They were a lot of fun, and given by one of the instructors
from the CA Sushi Academy. The instructor I had was Phillip Yi.
These classes aren't aimed at those who want to become professional sushi chefs, but were very informative and did give hands-on instruction in making various types of sushi.
I learned a lot, and have used what I learned on several
(link to Sur La Table's Cooking Classes Index