This thread is still ridiculously old but hopefully some gets around to responding. I'm considering Mario Kart, but the only problem is that I have literally no one to play it with. I no it's fun but I'm not big on racers. Anyway what should I be looking at. I already have SSB & Wind Waker (as per a few of your suggestions.)
Add me btw if you ever wanna run some smash. Nintendo ID - A.Newh0pe
A little info on what you like would help us help you find new experiences to love (And not just for wii u....)
For Wii u right now there is a lot of truly high quality stuff. Truly truly high quality stuff.
For skill based action games, Wonderful 101 and Bayonetta 2 are some of the best in the genre.... Ever. The games are chock full of content and replayability, with tons of unlocks, and reasons to replay levels again (And find new things you couldnt before).
Hyrule warriors is an action based romp with lots of meaty content.
Mario Lart 8 is a fantastic kart racer, even if you are single player only (although the wii u has free online gaming, so if you have internet, you can play with others). The track design is... Most unlike most racers you have played, and is very entertaining, even without the zany combat antics.
Captain Toad is a fantastic looking puzzle platformer with aastounding production values and visual design.
If you need your exploration adventure itch scratched... We still have some waiting to do, but man does it look like it will be worth it, Xenoblade chronicles X, and Zelda Wii u look amazing, and to be coming out within the next year or two.