One of the reasons I go back to my Wii is for the Virtual Console. A plethora of retro games to choose from guarantees you'll never be bored.
That was a huge selling point for me as well, initially.
But then a year later I started fixing up my older consoles/replacing/buying them, and now I never use my the virtual console. I also put emulators on my wii so if I want to play one of the games I own, I don't have to pay for another copy or wait for it to be released on the VC.
Still, if you don't have the older consoles and don't feel like putting the time, effort, or money into tracking down the games, the virtual console is a great alternative. I remember when I used it they would always release shitty games and would hold out on the good ones that everyone wanted... haven't checked it in awhile, I wonder what games have been released.
Also I dunno about anyone else, but the best part of the wii for me is the multiplayer games. I very rarely play video games when I'm alone, so the games that I tend to want/buy are the ones that are fun to play with a couple of friends. That seems to be what the wii specializes in. The only games off the top of my head that I ever play(ed) for the wii on my own were Metroid Prime, Animal Crossing, and Twilight Princess. All the other games I have were fun to play with others.