Holiday in New Zealand

Hello!
I've finally booked my flight to New Zealand (Auckland in June for 3 weeks), but I'm still looking for an interesting hotel..
Maybe someone could give me advice? I'd love to live in a hotel that offers spa services, has a speedy internet connection and good food. OR: A nice hotel and good restaurants close by.
I'm not looking for b&b places, youth hostels and the such...

I'd also appreciate any advice on "insider" tips for sighseeing :) I wouldn't want to come back home and then realize I've missed amazing things..

Thanks in advance,
Birte