I wouldn't buy a Wii, at least, not yet. I have pumped in more hours into Wii Sports Bowling than I have into many "real games." But that has to do a lot with the fact that I generally only play the Wii at my friend's house, so there's usually at least 3 or 4 of us, which makes bowling a perfect backdrop for hanging out.
I'm still waiting to see some real games come out on the system. The mini-game games are neat and fun for awhile, but I have to see Mario and Metroid before I'll admit the console is capable of some deep and engrossing games. So far the only "real games" have been slapped together ports that are really poorly executed.
For the time being, I wouldn't buy a Wii. Wait until something on it does interest you, then buy it. Who knows, the price might even drop between now and then.