Bulgogi is easy to make for a crowd, and japchae is not all that hard either. You could pick up side dishes at the Korean market to serve with the bulgogi, if you go that route. And you might also be able to get kimbop, which we were served EVERYWHERE in Korea. This recipe serves 4.
Combine all ingredients except meat for marinade. Stir until
sugar is dissolved. Add meat & toss to coat. Marinate 30 minutes or
up to overnight. (I actually do this in a large ziploc bag. I can cook
what we need, and I keep the rest in the freezer for later use.) Grill
meat in a high broiler, on a rack on bbq grill, or my favorite, on the
George Foreman grill, and cook to a nice glossy brown.