Do as much prep work ahead of time as your refrigerator will hold. You could peel and cut the potatoes and leave them in water in the fridge. You could blanche the green beans a day ahead too. If you're not using a fresh turkey, leave a couple of days to defrost it. I agree completely with the oven bag for the turkey. Also, Thanksgiving IS a community holiday -- asking people to bring their specialties is a great way to go.