I am not a vegetarian (I don't eat all meat, only seafood and poultry), but I do remember there being a great deal of sides and salads that would be vegetarian friendly.
When you make your PS, you may want to mention that you are a vegetarian. I have read that, upon request, the chef will walk you through the buffet, and let you know what you can and cannot eat. At times, the chef has even created a vegetarian main dish for the customer, as well.
As buffets go, I think Boma would be the best for a vegetarian, as they have many non-meat options.
I have had both dinner (2x) and breakfast (1x) and definately prefer dinner. Breakfast seems to be more traditional fare, while dinner is an adventure!
Enjoy!