if i may hijack a little, xmas pressie for a 6 year old girl who loves mario bros on the DS. what would be best, wii mario bros, mario galaxy or galaxy 2?
My boys are 7 and 8, and love all 3. Mario Bros is definitely best as multi-player though, so it depends if she'll have anyone else to play with. Both Galaxy's are superb games, but get very tricky in the later stages. Depends if she'll get annoyed with that and turn it off, or just practice a lot to get past.
As to the OP, we don't use the online stuff much, to be honest, apart from swapping Miis with other family Wii owners. No help there, sorry.