No More Heroes, some of the Wii Play minigames, Art Style: Orbient, Bomberman Blast.
No More Heroes grew on me after 2 or 3 bosses, but the first level is still bland and poorly designed IMO... and the overworld is pretty bland too.
The Wii Play games that I don't think look good are the fishing one, and the find Mii and Pose Mii ones... though I guess it would be difficult to make the latter two more interesting.
Art Style: Orbient I feel misses a big opportunity to look great... I think it (models, textures and such) was probably designed in about 15 minutes, they could have made it beautiful with a few little lighting/particle effects.
Bomberman Blast... Well I just don't like it.