We only have 3 games and the wifi in the wiiU is too weak to stay connected in the living room. Still it is almost used daily. Nintendo land got the least play time. We completed Super Mario U twice, all stars. Lego city undercover all 4 profiles story complete and tons of extra stuff done. My 4 year old still wants to play Lego city daily. Today he was chasing the steam train on a horse, playing out the toy story 3 opening in his mind.
Nintendoland: 20:09 (played 22 times)
Super Mario U: 292:35 (played 184 times)
Lego city undervover: 282:06 (played 117 times)
It has to be said that my kids leave it on a lot of the time.