I've got a few suggestions:
Mario Kart Wii
Legend of Zelda: Twilight Princess
Metroid Prime 3: Corruption (really good game right here IMO)
Animal Crossing: City Folk (if you like that sort of thing; i mean, I do).
Wii Music
Also, I too have played Brawl with my siblings, and it is by far my favorite Wii game. =) I'm still trying to convince my parents to give it a try; they liked Mario kart Wii, so...yeah.
ANYWAY, there's my two cents.
-MusicGamer