Best way to see the South Island is one of two ways. If it was me I would drive from Christchurch to Mt Cook National Park and stay in the Hermitage hotel for the night, most amazing view of the mountain in the morning. Helicopter Line run AS355s on sightseeing trips up the glacier from there and around the summit of the mountain with landings etc etc.
From here drive through to Queenstown and Te Anau. Both have plenty plenty helicopters and I have some good friends who I know will be able to chuck you and the missus in their back seat for a flight or two. Make sure you take a language book as many of the Chop Suey brigade live down this way. Then head up through Wanaka, through Haast Pass and up the wild and rugged West Coast. This is some of the best part of the country and the helicopter hunting from this region is the stuff legends are made of. James Scott still runs a couple of 500Ds on deer recovery out of Fox Glacier. Fox and Franz Josef both have glacier trips, either walkinmg or flying. Kelly who is the base manager for Glacier Southern Lakes helicopters is a Canadian so might be able to wangle a ride or two with him.
Then carry on up the coast through Hokitika, Greymouth and then through some wilderness areas to Karamea and enjoy the beaches up there. Across to Nelson and then over to Blenheim for a long awaited sojourn through the best wine country Kiwiland has to offer. I know all the best spots there
If you are keeping van then straight onto the ferry, if not then drive from Blenheim to Kaikoura and down the coast back to CHC. Hope that enlightens you. The south island of NZ is the best part. North Island is nice but not as good as south. Are you into fishing, if so will arrange a days helifishing for you when you get here to AKL.
Heli Ops