Thanksgiving requires a lot of planning, cooking, timing, and logistics with family and friends. Don't add wine stress to the ocassion as well. Understand that a lot of wines will work just great with the big meal, especially if it's a relatively traditional turkey day meal. Let me walk you through some ideas.
My first advice is this: if you have a big casual group of people make sure to have several wines including at least one red and one white. Seriously, how much time is spent actually sitting at a dining room table and how much time is spent standing in the kitchen, roaming around the house, leaning up against the wall in a crowded family room watching the Detriot Lions, or listening to your distance cousin talk about the economy on the back patio. In this situation, have both a red and white on hand- and plenty of it. I recommend California Cabernet Sauvignon or "Meritage" blends, California Syrah or Petite Sirah, and Washington state Cabernet Sauvignon or Syrah.
For white wine, you could reach for a moderately oaked California Chardonnay for the mainstream popularity but let me provide a couple other suggestions in keeping with the American wine theme. Ask your local wine merchant about their selection of Oregon Pinot Gris, Washington state Riesling, New York Riesling, or California producers of Rhone white wines varietals such as Viognier and Roussanne. My first pick out of these would be Oregon Pinot Gris.
In a smaller gathering and a more formal meal, serve a red wine at the table that's versatile. My top pick is still Cabernet Sauvignon with a little bit of age on it. Even more specific, I'd go for a Sonoma County wine or a Napa Valley producer who's focused on a more refined Cabernet style. Other wine regions such as Paso Robles, CA, Columbia Valley, WA, and Walla Walla, WA, also produce Cabernets and Cabernet blends that are fitting. In the spirit of a uniquely American holiday, serve American wine. There are plenty of other opportunities to open your Bordeaux.
You might be surprised that my top pick isn't Pinot Noir, but I find that all the wonderful subtleties of a good Pinot are washed away in the Thanksgiving day meal.
In any case, don't take wine and food pairings too seriously on Thanksgiving so that it adds to your stress level. With the variety of flavors involved and the number of side dishes that grace most tables, versatility is key. I will be pouring a beautiful Cabernet, probably with a few years of bottle age. Maybe several of them. Now raise a glass!