We have done Thanksgiving at our house the last few years for our families, and we may do it again this year. I think we planned for 40 last year and ended up having around 37 guests. Immediate family for the most part.
Pretty typical stuff: A turkey or two (we brined ours last year, and SIL brought 1 slightly burnt bird). 10-20 lbs mashed potatoes, a gallon of gravy, 8-10 lbs each corn, green beans, baked beans, stuffing. Broccoli casserole, green bean casserole, squash casserole, mac n cheese, cranberry gel, sweet potatoes, artichoke dip (fellow poster Simple Girl's slightly modified recipe!), italian bread, papaya salad, egg rolls, spring rolls, pad thai, other weird Laotian/Thai/Cambodian food I can't remember, regular rice, sticky rice. I know we had some desserts but I think I blacked out into a food induced coma before I had any sweets. Maybe pecan pie, pumpkin pie, chocolate cake, pumpkin rolls, banana bread?
I asked a few people to bring a dish to help out, since we have a tiny old in wall oven and can barely fit 1 turkey in it. It took a bit of logistical masterminding to get everything hot and ready concurrently but we pulled it off perfectly without too much effort. Maybe a few hours in the kitchen the morning of Thanksgiving, plus a 7 am wake up call to get the bird in very early, and a little thawing/brining prep 2 days prior.
One thing we learned is that cooking for a meal for 40 is only 2-3x the work of cooking for 4 if you have big enough pots and pans. And willing children who can serve as mini sous chefs.
It does get a little Gordon Ramsay up in here at times though...