Thanks for the replies - I'm not too worried about what others think though I plan on being respectful. IMO a shirt and tie is approriate attire but I just wanted to get an idea of what I should expect. These repsonses helped.
It is obvious that many folks enjoy to dress up for dinner but I'm sure there are an equal number that find it to be a hassel. Especially if the expectation is a full suit or tux. My only problem with this is that if I choose not to go to the formal dinner I don't get the Lobster or Prime Rib. If they provided a less formal area to get the same food then I have no problem with the formal dress code being strictly respected.
Thanks again - not much longer till the big day. Everyone at work is sick as a dog. I have a giant stack of disinfectant pads in my office! Nobody is touching my mouse, keyboard or phone without a thorough cleaning afterwards.