I can't add much additional to this thread as my thoughts had been addressed by page three. I would like to offer some general variations to sum this up for Tati.
The "traditional" meal is turkey with stuffing, potatoes, gravy, veggies, cranberry sauce (has that been mentioned yet?) in large quantities followed by dessert that is usually pies...pumpkin, apple and others. We then go into regional and ethnic variations that add a lot of variety.
Debbie has provided you with some Southern variations including oyster stuffing, turdukin was started in New Orleans I believe, some have mashed potatoes, others have candied yams or sweet potatoe souffle (or pie) and desserts like pecan pie (that has now become fairly widely adopted). Deep fried turkey has also become a bit of a trend.
Then like Tigsmom said, our many ethnic groups add some of their specialties. (Where are the pierogi, Tigsmom?)
Oh, for the turdukin, there are separate "stuffings" between each layer to keep the flavors separate.
As for the cornucopia, one alteration I would suggest is that I am more used to them being filled with fruit and nuts rather than decorative gourds. I usually have the "responsibility" of assembling them for family meals.
Due to the number of people, we often have "adult" and "children" tables, much to the displeasure of the older kids that want to "graduate".
As per the start of the Christmas season, at the end of the Macy's parade, the last float is Santa's sleigh signaling the "official" start.
Decorations tend to be subtle and indoors. Flowers, the cornucopia, turkeys, pilgrims and corn.
Many high school football championship games are played as well as college rivalry games.
While I shudder to call it a tradition, the first of the Christmas programming is also aired in the evening. It's a Wonderful Life and A Christmas Carol usually have their first of many airings.