Here are a couple of wii games which my 5 year old son enjoys playing (he started playing them an year and a half ago):
New Super Mario Bros U: This is a multiplayer performer in which surprises and secrets abound and is perfect for young kids of the above mentioned age group.
Just Dance Juniors: All the best features from the older Just Dance games have been taken together and wrapped up in this one with both Nursery Rhythm and Classic Children's Pop. The dancers are also all of the younger variety so the kids will love it.
Bonsai Barber: One of the best makeover games on the wii till date. The friendly plants and steady progression makes this great for really young players.
Apart from the above mentioned games, [url=.compet/]pet games[/url] like these could be enjoyable to play together. It isn't exactly (exclusively) kids' stuff, so both you and your kids are bound to have fun playing it together. All you have to do is adopt a virtual pet and collect the local currency of the virtual land to take care of him. Kids can also learn how to buy and sell virtual stocks with this game.