For a nice hotel, try the
Millennium - I haven't stayed there myself but have heard good things. Rooms start at around the NZD 200 mark. If you don't mind being a little ways out of the town centre, you might also consider
Millbrook - Bill Clinton seemed to like it
If neither of these appeal,
www.jasons.co.nz and
www.aaguides.co.nz between them list most accommodation providers.
justakiwi