Two words - frisbee dog!
I liked Wii sports, but was getting fed up with playing the same sports and never quite got the hang of home runs in baseball. Wii Sports Resort has a huge variety of games and levels and while I try to play them all, my favourite has to be Frisbee Dog. The medals on each game mean that you can try different ways of playing, including trying not to score at all on one game! The addition of the motion plus adaptor makes the games more fun and is simple to use (although there are occasional glitches) and i'm not too fussed on the loss of the wii fitness tests as i've got wii fit plus anyway. Most new wiis are being sold with this game, but if you haven't already got it, i would say it's a must have.