Many people, judging by your game library, would label you as a 'casual gamer'. Most 'good' multiplayer games will probably be more fun for a 'hardcore' gamer, but here are a few:
Super Mario Strikers Charged - Now Available
Battalion Wars 2 - Now Available
Medal of Honor Heroes 2 - Now Available
Super Smash Bros. Brawl - March 9
Mario Kart Wii - [Rumoured] April 2
In bold are what I, among others, consider to be the best two multiplayer games that will be on the wii for quite a long time. Some may even go as far to say that they will be the best games the wii will ever recieved, and both will definetly be candidates for 'Game of the Year 2008.'
Another fun multiplayer game would be WarioWare: Smooth Moves, which is also now available. It puts the gamer against their opponent in a wide variety of extremely short 'micro games' which attempt to use the wii-remote to its full potential.