Did this just last year for a family reunion that ended up being about 75 people.
Had two grills, a boatload of charcoal, a standalone burner/cooker (for rice, see below), an alarm clock that went off at 0400, and a ready supply of adult beverages: in best order as I can recall
2 each about 15# briskets
3 each about 15# Turkeys
4 each Red Salmon (8 Fillets)
4 large chunks (maybe 10#'s?) of halibut
More than I care to remember of store-bought king crab
Huge bowl of chopped lettuce
Huge bowl of various chopped veggies
Mixed lettuce and veggies for salad
About 4 gallons (:) ) of steamed rice
10 bags of dinner rolls
Butter
Dozen boxes of crackers served with the king crab (steamed) for appetizers
Salad course
BBQ'd beef, turkey, salmon and halibut....all in all about 10 hours to cook + most of a day ahead of time marinading the brisket, rubbing the turkey, and chopping vegetables.