Here today, gone tomorrow. That's the fate that befalls many new restaurants, but it's one future Keè Grill is likely to avoid. The keys to its success? Well, the simple, well-executed, tropically influenced cuisine includes macadamia-nut sautéed shrimp, crab-shiitake-crusted grouper, and grilled veal chop. The waiters are courteous and well trained. And the management is thoroughly professional. But the only key that gets you through the door is this one: a reservation, usually made days -- sometimes weeks -- in advance. And don't forget to write down your assigned reservation number. Lose it, and you're locked out.