My 7 year old and I have been enjoying the heavenly delights of 'Legend of Zelda: Skyward Sword' it is an amazing adventure fantasy if you are not already familiar with the world of Zelda. The motion control and nunchuk are used as the word and shield and many a battle has been won already. It is better than the previous iteration' Twilight Princess'
The Resident Evil series is also are available on Wii for adult gamers if you're into shooting zombies and so is 'Silent Hill'. The 'Lego Indiana Jones' and 'Lego Harry Potter' are good fun. 'Tomb Raider Underworld' and ' Prince of Persia- Rival Swords' can all be picked up from bargain bins.
although it doesnt really class as adventure ( more of an adventure/platform) the best games on Wii are the super Mario Galaxy I and II... I could go on but I'll stop. Hope this helps.