My kids use theirs too much
When the kids misbehave I ban them from the Wii. I can do that because they love it (two boys, 8 and 6). I know when they are teenagers they will want a hardcore gaming console, but for the next 5 years or so I'm sure they will continue to enjoy the Wii (bought for Christmas 2006).
We have about half a dozen Gamecube games that they really like - Mario Kart Doubledash (sadly, soon to be displaced by Mario Kart Wii), Luigi's Mansion, Windwaker, Monopoly and Mario Dance Craze (with a dance mat, and surprisingly good fun).
They love the virtual console games (I wonder if they are included in the games-per-console figures?), especially Paper Mario and Mario 64. In fact, I played through Paper Mario (25 hours accumulated play time omg), and both my sons have played that through twice themselves. That's a hell of a lot of value out of a £4 game.
As for actual Wii games, Wii sports is of course great, we have Ravin Rabbids (apparently Ravin Rabbids 2 is even better), Super Paper Mario (massive let-down after Paper Mario), Fifa 2008 (can't stand it myself but my eldest loves it), Galaxy (astonishingly good), Twilight Princess (put in about 20 hours but got stuck), Star Trek Conquest (utter rubbish), and Mario Strikers Charged (got supplanted by Fifa 2008). I also have Resident Evil but I don't let the kids play that one. The Wii is perfect for that sort of game and I'll probably buy House of the Dead too.
I just bought Mario Kart Wii for them, as I said, so it looks like we'll be playing that solidly for the next month or two. I'm hoping the Network play will be good as the Wii is crying out for this.
Finally, we will of course getting the balance board when it comes out - really looking forward to that.