I was going to say lasagna too (make ahead and freeze it). Or spaghetti. That's easy too if you make the sauce ahead.
Are you driving? Do you have and can you take your crock pot? There are TONS of make ahead frozen crockpot meals that you prep ahead, freeze and then throw in the crock in the morning - fajitas, white chicken chili (regular chili), cheesy chicken casserole (I just made this last week and it was delish).
Tacos are also easy and feed a crowd. Do your meat ahead of time and freeze it.
For Thanksgiving, if you want to stick with a traditional meal, I guess I'd still do my turkey & stuffing as I usually do (in a reynold's oven bag), Or, if you want to get real easy, just do turkey breasts and stove top stuffing. I premake my mashed potatoes and sweet potatoes, so you can premake those in throw away pans, just do corn (no fancy casseroles that have to put together), beans or cooked carrots, rolls, canned cranberry sauce and take Mrs. Smith's frozen pies.
Are others helping with this or are you doing all the food? I think I'd assign each family a night to prep dinner for the crowd.