Mario Kart - It is extremely fun, no way you don't pick this one up.

Okami - One of my favorite game series is Zelda, and I saw you have a few Zelda games, so I suggest you get Okami. So far I've played ~20 hours and I love it. The brush is excellent, and the graphics are beautiful. The story can be a little overwhelming, but overall it is good.

Fire Emblem: Radiant Dawn - If you looking for a longer and challenging game, this is your choice. It is a strategy RPG, and if your not familiar with them, if you like chess and other strategy games, you'll probably like Fire Emblem.

No More Heroes is brilliant, Mario Kart is also excellent, get both if you can (i.e mario kart is in stock).

I'd go with the 3 you're already considering.

Mario Kart - great local and online multiplayer

No More Heroes - great single player

Boom Blox - LEVEL EDITOR

I wouldn't recomend it as highly as the three listed.... but Medal of Honour Heroes 2 is a decent option based on your "owned games" list.

It's a really fun shooter. Okami as well since is Zelda like.

Those are two more i'd put on your list of games to buy when you get the chance.

No More Heroes an Okami

Mario Kart Wii, Okami and Resident Evil 4.

Mario Kart Wii, it has the longest lasting appeal because of the online multiplayer. It is a must have in any Wii library.

Mario kart Wii. I have never heard of the other two games.