In addition to Jim’s questions, what kind of service are they expecting? Will dinners be serve plated or using waiter service at table? As a veteran of such events for 2000+ the big factor in my mind is having good people…and that is a BIG nut to crack!
Where one or two people can effectively run a sit down kitchen and dinner with lets say 8 – 10 tables, once you get much bigger, you need multiple "teams" each handling a certain number of tables. Our approach and menu was not terribly different whether it was 10 or 200 tables. The bigger events just required more teams doing the same thing and some good supervision of those teams.