Coincidentally, we had a few people over for a Wii party today, and played Wii Sports (though we never got to golf). It was a tremendously good time. I'm not sure how much staying power it would have for repeat visits, but everybody had a great time, from the moment I sat them down and made them make Miis to look like themselves (or each other, in the case of one couple). :)

I also like tennis the best. I particularly like cooperative play so we can play without a split screen. Bowling and baseball are fun too...

The main problem with the Wii is the lack of a huge number of good games. Zelda is great though, you might enjoy that (though it's not a true RPG). I hear Super Paper Mario is neat too, want to pick that up. And don't forget the Harry Potter Wii game coming out in the not-so-distant future, where you can apparently use the Wiimote as a wand! ;)