My recommendation is:
Wii Play
2 Extra Nunchuks
Extra Wii Remote
Gamecube controller OR Wii Remote + Classic Controller if you want a fourth player
This way you and your siblings will each have a Remote+Nunchuk plus an extra remote when someone comes over. I don't think you will ever need 4 remotes + 4 nunchuks (there aren't many games that use that) so you're better off with a Gamecube controller or a Remote + Classic controller for the fourth person.
For the fourth player the Remote + Classic will be much better (for Wii Sports) but the Gamecube will be a lot cheaper (you can get a 3rd party controller for $10). Since I'm assuming money isn't a huge factor (might as well splurge all the way) I'd recommend the Remote + Classic. The Classic is only for 4 player Brawl and Virtual Console games.
Wii Play has a couple fun multiplayer games and it's only $10 plus remote.
I'm sorry if that's confusing, but let me know if I helped.
Good luck!
# of games above 75 on Metacritic (including downloadable):
360: 241 DS: 144
PS3: 152 PSP: 126
Wii: 85
