No matter which of these meats you choose to put over the flames for your posh grill dinner, you're going to have a triple-header on your hands: a meal that is fun to cook, seems impressive, and tastes great. And besides, if you have trouble thinking of anything other than work to discuss with your boss, you can always talk grilling - it's the one cooking method that everybody has an opinion about.
The single most popular, and also the easiest, choice for the high-end grilling meal is a steak. Remember, though, that this is a special occasion, so sirloin simply won't do. Instead, go for either a rib-eye or a porterhouse. The rib-eye is basically a prime rib cut into steaks, which means it has all of the tenderness and the rich beef flavor of that classic roast. The porterhouse has even more going for it, since it contains parts of two different muscles. One side of the bone is the tenderloin, the most tender cut of beef of them all; on the other is the top loin, slightly less tender but with more beef flavor.
Whichever steak you choose, make sure you get a very thick one, at least two inches. You'll want to get the steak deeply charred on the outside - that's what gives it that real grilled flavor - but rare on the inside. You will probably have to go to the butcher to get a steak this thick (or at the very least call your supermarket butcher a couple of days ahead), but it's worth it. If you want to make sure you have the very best steak that money can buy, look for one labeled "prime," which is the highest grade of beef, extremely tender, flavorful, and juicy. If your butcher doesn't have prime (the majority produced in the U.S. is sold to steakhouses or shipped to Japan), go for "choice"; it will still be a great piece of meat.