What is this, LAX? The Top of the Port, the restaurant in the towering Miami International Airport Hotel, is a genteel Continental eatery. But its lobby, located on the departure level, is now a bustling sushi bar. For those of us sick of Cuban coffee and sandwich shops, the California rolls and tender tuna sashimi are a welcome relief from the humid, heavy heat. How the fare flies is a different story altogether -- raw fish, rice, and seaweed may not be the thing to settle a turbulent stomach on a rocky flight. But it sure calms the savage beasts we all turn into when we realize we're grounded yet again.