Super Mario Sunshine was a great selling game for the Nintendo Gamecube. The game sold around 5.5 million copies as of June 2006. This game would perfectly fit the Wii U.
The Wii U is no doubt going to receive some 3D mario games in the future so why not make one of those games a sequel to the fan favorite game. New graphical power and features can make the tropical paradise into a must have game for the Wii U.