Do you have people over to play video games or are you more of a solitary gamer?
I love the wii, but it's a party system (as with pretty much any nintendo system). If you don't play video games in big groups the wii is going to lose some appeal.
Again, I love the wii and I'm glad its the only new console I own (I want to get a 360 too). But there have been threads with basement-dwellers saying they got bored with the wii too fast because they played 200 hours since they got it by themselves. The Wii is an amazing system that brings new gameplay and even new types of games, but it's designed for more than one person to play.
I'd say test out a wii or 360 over a friend's house and see which you like better. whatever you do, dont buy a ps3