Nintendo Land
A more thorough, and multi-player, sit-down with Nintendo Land has brought me to a simple conclusion: the Luigi's Ghost Mansion game is the only one worth playing again.
None of the solo experiences - or multi-player turn-taking affairs - can hold anyone's interest after one or two tries. Admittedly, I didn't do the multi-player modes of Metroid Blast and Zelda Battle Quest, because they both require a bunch of extra equipment we didn't have on-hand (which is as good as a disqualification). Pikmin Adventure is just dreadfully boring. Mario Chase is too difficult to navigate to be fun, and the Animal Crossing fruit-collection game is ... okay, but poorly balanced: winning as the fruit collectors is almost impossible, and it only becomes less possible with more players.
Luigi's Ghost Mansion, a sort-of reverse Pac-man, pits one "ghost" player - invisible except in special circumstances - against some Luigi-alikes with ghostbusting flashlights in a maze-like arena. A hunter's Wii remote will rumble when the ghost is near, but the hunter doesn't necessarily know from what direction the ghost is coming -- which the ghost can exploit to great dramatic effect, legitimately haunting a player. And hunters which are downed can be revived with enough flashlight power, but replacement batteries are difficult to come by. Honestly, this game in itself can keep a party going for some time.
It's a shame that the rest of the package is mediocre at best.
Better than: Wii Play
Not as good as: Wii Sports
Keep in mind, for multi-player: you'll need to supplement the Wii U's equipment set with Wii Remotes, and more in some games (Motion Pluses and/or Nunchuks).
Progress: Gave Up -- Played a little of everything