I went to NZ in January 2010. I did two pelagic trips with Albatross Encounters out of Kaikoura which I very highly recommend.
I then went south to Stewart Island and did two more pelagic trips with Ruggedy Range Expeditions. These were 3 hour trips. Furhana, the guide, was very knowledgeable and we had great views of lots of albatross (Buller's, White-cappped, Northern Royal), both Blue and Yellow-eyed Penguins, Brown Skuas, Spotted and Stewart Island Shags, Sooty Shearwaters, Cape Petrel, and several (if "challenging") views of the tiny Common Diving Petrels. I highly recommend seeking them out if your travels take you down there (http://www.ruggedyrange.com/pelagic_birding.htm).
On the ferry over to Stewart Island, I was lucky enough to see both a Broad-billed Prion and a Mottled Petrel. I've posted some of my photos at http://www.flickr.com/photos/jimscarff/sets/72157623473187159/.
I then went south to Stewart Island and did two more pelagic trips with Ruggedy Range Expeditions. These were 3 hour trips. Furhana, the guide, was very knowledgeable and we had great views of lots of albatross (Buller's, White-cappped, Northern Royal), both Blue and Yellow-eyed Penguins, Brown Skuas, Spotted and Stewart Island Shags, Sooty Shearwaters, Cape Petrel, and several (if "challenging") views of the tiny Common Diving Petrels. I highly recommend seeking them out if your travels take you down there (http://www.ruggedyrange.com/pelagic_birding.htm).
On the ferry over to Stewart Island, I was lucky enough to see both a Broad-billed Prion and a Mottled Petrel. I've posted some of my photos at http://www.flickr.com/photos/jimscarff/sets/72157623473187159/.