We visited the Chinatown area and explored the port area including Nissin Cup Noodles Museum. Agree with you, Yokohama is small enough to explore in a day's trip. Nice, spacious, quiet walk tourists like us. But, surprisingly, Yokohama is actually the largest city after the special wards of Tokyo, in terms of population. 3.7 million of them. But we don't feel as crowded as Tokyo.