How about an Asian-style noodle bar? Pick a couple types of noodles, a couple types of broth, and some toppings. After the noodles are cooked, you can probably "hold" them in a warm water bath. Keep the broth hot in a crockpot or on the stove.
(Whatever broth you pick, infuse it with Asian-y seasonings like ginger, star anise, onion, mushroom, etc… you can make pho broth if you want to)
You could also have some very simply cooked veggies (carrots, celery, onion, mushroom, broccoli) and/or protein (chicken, beef, tofu) for people to stir in.
A big bowl of that would be nice, I think. It's filling enough to satisfy but lighter than the Thanksgiving fare.