This is probably just about do-able, although the South Island is massive.

Why have you been advised to stay away from CC? Is it because of earthquake risk? If not, then I would say spend 2 nights here. It's a nice relaxing city.

I would try spend 4-5 days in the Wanaka & Queenstown area as, for me, it is the highlight of any trip to NZ.

Te Anau is only worthwhile if you are visting Milford Sound, otherwise it's just a bog standard village.

Why Greymouth/Hokitika? Again, there is nothing special here IMO. I would much more recommend Kaikoura or Stewart Island or even the Otago Peninsula outside Dunedin.

In just under 2 weeks you shouldn't try to see the whole south island - I would do a loop from CC to Wanaka/Queenstown, then Milford Sound if you think you'd be interested and then back to CC via the Catlins and Dunedin/Otago Peninsula.

I respectfully disagree with pgriffin about Te Anau. It's hiking nirvana. If you don't like hiking, well there you go.

Many people plan a stopover in Hokitika as it's a convenient choice. It's known for it's greenstone (jade). Hokitika Gorge is well worth the detour if you have time.

Whether or not you find Christchurch worthwhile really depends on your particular interests. It's very much a city, so if cities aren't your thing... It's a city recovering from a massive earthquake and loss. There's a shortage of accommodation as a result, so you'll need to book well in advance. Many of the major tourist attractions are gone, some forever, but it's definitely a city desperately trying to recover. Walking the perimeter of the Red Zone is an unforgettable experience and the New Start Cashel Mall demonstrates the resilience of the residents.

One day in each location would never be enough for me, but we all have our own traveling style.

The usual 'must see's' for first time visitors to the South Island generally include Arthur's Pass (either by train or car), the West Coast (glaciers), Queenstown, Te Anau/Milford and/or Doubtful Sound, Lake Tekapo and Mt Cook (which are easy to combine as they're not very far from one another).

This distance calculator might help you in your planning:

http://www.newzealand.com/travel/getting-to-around-nz/travel-times-and-distances/travel-times-and-distances-home.cfm

Here's a map of potential white water rafting areas:

http://www.nz-rafting.com/