We go on large group,holidays every summer, there tends to be 20-30 of us, split approx evenly between adults and kids. We tend to feed the kids earlier, and because of fussiness (and sheer volume of numbers), there's often a selection for dinner - pasta in Tom sauce, pasta and pesto, plain pasta, grated cheese, pizza slices, crudités.
For the adults, again, there tends to be lots of food. We would BBQ prob twice minimum, with all sorts of things on the BBQ - steaks, fish, sausages, burgers, veggies. Then we make and buy accompanying salads, and make big trays of roast garlic potatoes. Once we made enormous paellas, we've done pizzas for all in an on site wood fired oven. And bought plenty of bung in the oven pizzas! We've also had on site caterers come for the odd night as a treat.
The key thing is that all adults are involved - there's plenty of jobs, making sure kids are ok, everyone has a drink, rubbish is dealt with, washing up and clearing away, as well as chopping, prepping etc. It's nice to be chatting over a glass of wine while prepping with friends. And many hands make light work!