If you are concerned about this issue, I urge you to email and/or phone the concierge folks well before your trip to speak to them about your needs. Let them know when you will be there, and ask them if things will be at least clearly marked as to what is vegan or vegetarian, and if they can suggest options for you.
Also, when you first arrive, ask to speak to Chef Dick (or another chef on any given day) and they will be more than happy to come out and speak to you about which items on the buffet are vegetarian. Make sure they also know how long you will be there (what days you are staying). You may be surprised, they may make an effort to " veganize" some dishes, or at least make sure things are clearly labeled or that some veg choices are available for you.
(of course, I have always heard they are really accommodating with these kinds of things, but heck, I couldn't even get my diabetic dad sugar-free hot cocoa packets when we were there for 10 days last December--which was pretty pathetic if you ask me, they were just Swiss Miss for crying out loud! Next time we'll be sure to contact them ahead of time, or we'll just bring our own I guess.)