Okami for Wii is the better of the two versions (Take that from someone who's played both, and owns the PS2 version).
For a 3rd game I would suggest Metroid Prime 3.
After that, Zack & Wiki, No More Heroes, Mario Kart, Okami, and RE4 Wii are my recommendations. MLB Power Pros. and Pro Evo 2008 if you like the respective sports.