The best game i had played on the wii is RE4, if you havent played it on other console, get this one, its going to last you a month if you try to unlock everything and playing it casually.

Next on, i would recommend Disaster which is going to release the english ver next month. The trailer and gameplay demo look promising and should be a game you dont want to miss.

If you like GTA style of games, get godfather blackhand edition. For me, is a really great games with over 20 hrs gameplay. Its also utilize lot of the motion control on the wii.

I am not big fan of zelda or metroid although those are the top games on wii, but i play them a while and leave it, not sure why, but guess its just not my type of game.

Also if you occasionally have friends coming over to play your wii, this below few games are a must have to play with your buddy:
Mario wii Kart
Wii sport
Warioware (this one is really fun playing alone, but last me 1 week till i unlock everything)
RE:UC and HotD2 & 3 (On rail shooter, if you got the money to burn, get the Nyko Light gun to play with these game).

Again, if you are able to play foreign games, try get Fatal Frame 4, is a surviving horror game, which i beat 2 times, and is fun and great.

Wii can play gamecube games, so if you are interested, get Remake and Re0 as well, to complete the surviving horror saga. Both are excellent games during the cube era.

All this will last you for roughly 3 month till next year. THen we wait for the next coming games

Hope this help. If anything, just ask around Happy gaming.