i'm with elfie and sha-ront.
my first thought was clam-bake-ish, or what those from down yonder call a low country bawl.
since everyone except a rare freak loves italian food, and you're feeding a bunch, i was thinking pasta. since it's a beachy thing, and you're looking for a little sophistication, how about a bouillabase/cioppino/zuppa di pesce to go with or over the pasta?
it doesn't take very long to cook. in fact, too long will ruin the fish by making them tough. just make your base sauce or broth, which can be done in advance, then add the thicker pieces and shelled fish first. wait 2 or 3 minutes, then put in the the more delicate fish a few minutes before serving.
i'd add lobsters, clams, mussels, shrimp, scallops, squid, and a chunky, firm fleshed white fish like monkfish, pretty much in that order.
brown your garlic (lotsa garlic - sliced, not chopped) and diced onions, deglaze with wine, add a little fish stock or clam juice, a bundle of fresh herbs de provence, add chopped tomatoes, let simmer to bring flavors together, then begin to add fish. you're ready to serve with the pasta in just a few minutes, and it looks great steaming in large bowls. or if you think there might be lobster horders, get an assembly line and dole out portions in pasta bowls.
if you really want to knock them out, bake some crusty bread to serve along with it. the smell of fresh bread (
easter had better get here soon!), the fish in herby garlic broth, and the ocean is not something to be missed in life.