Paper Mario and Mario Kart 64 are both excellent titles. I'd probably call both of them "must-own" without hesitation, although if you've already played the originals, then you could probably get by without them on the VC, and if you were to choose one I think the deciding factor would be whether you use the Wii more for single-player (in which case Paper Mario is the best choice, as an enjoyably replayable breezy RPG) or multi-player (in which case Mario Kart 64 is the obvious choice, as it is Mario Kart).
But yeah, weird how long this has taken, relative to the iOS version.
"I think it's the idea that counts, not the actual method. As long as you set out to cause a horrible death through insects eating the person, you're good." - apenpaap