We got a W11 for christmas last year, my DD was 7 and DD was 5 1/2 They were both able to play the games, ( my personal therory is that most games more or less play them selves as long as you push the right buttons the bowling ball with generally roll in the right direction. yes you can throw it backwards but it takes some effort to do it)
We started off with Wii sports and stuff like that bowling, cycling, boxing, tennis. I was ok with that, they were playing together, taking turns, getting a little bit of aerobic exercise.
DS recieved LEGO starwars in May and has totally been obsessed and super annoying about it. He wants to play it constantly, He plays it alone because his sister isn't interested. and he stands there like a zombie. I dont see anything at all educational about this particular game or Mario cart. I limit his time, but its a constant struggle. IF i allowed him to chose he would do it 24/7, I don't allow it. I'm not perfect and while i wish i had the follow through, it might a great motivator, but for our family it hasn't been a good reward, like clean your room and you can play, instead i have to go in and make him redo his chores 5 times because he rushed because he wanted to play, I get frustrated and at 6 time i give up, tell him he didn't earn it and then there is a whole pouty mess.
If you really stick to a limited amout of games sports ones and learning company onesyou might be ok, but personally I think your kids are young to get hooked on these. At the ages your kids are, they are happy to build with blocks and use art materials like playdough and markers, Save the video games until they move through that stage.