Yokohama Bay Bridge is the big white suspension bridge across the port, best known to visitors for the Skywalk observation area attached to it. The view looks back toward Minato Mirai and the working harbour, so it is most rewarding if you already like ports, bridges, and city skylines.
Check opening days before going, as access to the observation area is limited and can vary by season. The trip out is more effort than the central waterfront sights, but the angle on Yokohama's bay is different enough to justify it for bridge and harbour fans.