RPG's: Fire Emblem is already there, this holiday you can play Tales of Symphonia 2 and Little King's Story, in 2009 Fragile, Arc Rise Fantasia, Final Fantasy CC and if it reaches the West Oboro Muramasa. And I'm sure more will come.
Action/Adventure: RE4, No More Heroes, Okami, Zack and Wiki. Coming: MadWorld, The Conduit
Nintendo: Zelda, Mario Galaxy, Brawl, Kart
Virtual Console: (this is THE best feature of Wii) dozens and dozens of NES/SNES/N64/Mega Drive/NeoGeo etc games!
You probably never owned a Gamecube, so you can play REmake (best Resident Evil ever), Eternal Darkness, Tales of Symphonia, Skies of Arcadia, Baten Kaitos, RE0, WindWaker.
I think a Wii offers great value next to a PS3. It gets a lot of exclusives.
Edit: you're not sure what the future will bring for Wii: well, since it's steaming for 50% marketshare and beyond you can be assured that more and more games will come to Wii. Best thing, most of these will be exclusive.
