resident evil 4 if you never played it. might seem a bit dated, but if you enjoy the series it is a must buy.
erm... boomblox is a lot of fun, and family friendly.
smash bros, but only if you have a group to play it with because the online isnt too good.
pretty much any major nintendo release... so that is smash bros, mario kart, mario galaxy (amazingly amazing if you dig platforming), metroid and so on and so on.
really, if you are into games like CoD... the wii is not a system for you, but the family will enjoy it!