Hi. We have three girls (10 w/special needs, 8 and almost 4). They have nintendo ds too (highly recommend). Before we buy any wii or nintendo ds lite games we check out the ratings on ign.com. Ign tells us if the games are going to be to hard for the kids for the age group the game is geared out (for example, some games like The Little Mermaid for the ds are aimed at young kids, but the game does not speak, it requires the young child to be able to read all of the instructions and so it is not a recom. game). Anyway, here is our list:
MarioKart (highly recommend- my husband and I play it too with them) Mario Party 8 Elebits PaperMario (not sure if they know exactly what they're doing but they do it for hours) Mario Galaxy (again, not sure if they exaclty know what they're doing besides collecting stars, but they play for hours)
I was not impressed with Warioworld. If you have boys, the might like Zelda or Lego Star wars (my husband likes these and they looked appropriate for kids--my girls are more into the girl games and anything with Mario.
We are about to buy Disney Princess game for $20 because all of our neighbors girl's love it. If you have any questions about nintendo ds lites for your kids let me know--we have over 25 games and love the system.
Get a charger dock for the controllers (cheap on ebay) and some controller protectors so when they drop your $40 controllers they won't break :)
Diego games for both the Wii and the Ds are very fun and easy. It will show you along the game how to use the remote for play...My son also love the Ben 10 games...For girls, My daughter loves the dance games, she is 9.
Wii Ski is great fun and not difficult. My son also likes Spongebob Atlantis Squarepantis; it seems to be the easiest Spongebob game we've tried. I agree with the others that Mario Kart is a great one for kids. We also love Carnival Mini Golf for the kids. My daughter really loves the first Littlest Pet Shop game, although there is quite a bit of reading involved. You can have fun without reading, but to advance in the game you need to read and answer all the mail. When we first got our Wii, be got a gamepass from the local video store and tried out a bunch before buying. It was a good idea, as there were a few we thought would be a hit, but turned out to be duds for us. Enjoy!