[Question] Planning on getting a Wii...

For multiplayer that hasn't been mentioned I recommend some of the VC titles if you don't mind older stuff.

Dungeon Explorer is like an older Gauntlet if you can stomach the age and plays with up to 5 people. There's Bomberman '93 also for that many people. Obviously Mario Kart 64 if you can afford the extra classic controllers/GC controllers to fill 4 slots. Several nice 2p coop games too like Gunstar Heroes, Streets of Rage 2, etc.

Mario Party 8 I would advise against. I don't know if it's me but the unlocks were rather fast to get this time around, especially the minigames. Then again, it is the newest installment in the franchise.

Big Brain Academy Wii Degree you shouldn't get. It's pretty fun at first, but painfully limited in retrospect. You'll quickly notice the same games within less than 30 minutes, and there are very few of them when you realize you've played them all.

Warioware Smooth Moves is really a blast if you and friends don't mind making fools of yourselves. Many microgames and the sheer randoness prevail. What we do when we stop snipping each others' ropes in Lifeline is go to the 1p player file and then try to beat my record for the Super Fast tower.

Jam it back in, in the dark.