In the States, Thanksgiving meals and traditions can vary from region to region and from family to family. The only thing consistent feature across the country is turkey. In fact, many Hispanic Americans call Thanksgiving Day (in Spanish) The Day of the Turkey!
I agree with the poster who said that Thanksgiving kicks off the holiday season. After Thanksgiving, it's one Christmas party after another for the next 4 weeks. Families who do the Kris-Kringle or Secret Santa gift exchange for Christmas usually pick names at the Thanksgiving Day celebration - so it's handy for that too. If no Secret Santa, it's also just a good time to find out what type of gift loved-ones might want for Christmas.
Being from NOLA, we do our own creole/cajun version of the Thanksgiving Day meal - which people in other parts of the country might find sacrilegious: Fried Turkey, Root-Beer Glazed ham, Collard Greens, Baked Macaroni, Corn Bisque, Gumbo, Stuffed Merliton, Oyster and Crabmeat Dressing, Sweet (like-cake) Cornbread, Dinner Rolls, Sweet Potato Pie, Pecan Pie, Bread Pudding with Whiskey Sauce and spiked Eggnog. Gravy is not a big element - as the mush of the macaroni, dressing, and greens is more than enough! At the end of the meal, there is always enough food for each family unit to take home a pile for leftovers. Nothing better than Thanksgiving Day leftovers.