the only reason why I would play GCN games on my Wii over my GCN is because the Wii is component cable compatible, where as the newer models of the Cube are only Composite or S-Video. People with earlier GCN models most likely will have that shnazzy component cable input...Finding GCN Component cables on the other hand is like going out and searching for peter pan pirate treasure.lol
I'll be playing Super Mario Sunshine on my wii, that's a given...Whenever that happens. 
I also have the usual suspects like Mario Sunshine and Wind Waker and I like Splinter Cell old games compared to the new like Pandora Tomorrow and Chaos Theory.