Hi, Darren,
You have a lot of one-night stays. What are you planning to do in these places, because I don't think for the most part you are going to have much time to see anything other than the road. Distances in NZ can be deceptive and take longer than you think.
Perhaps if you let us know what you are interested in we could offer some more concrete suggestions.
Schools will be on holidays during January so in tourist places like Queenstown, Te Anau, Milford, Franz / Fox Glacier, and Mt Cook it might pay you to prebook your stays once you have your itinerary sussed.

I think you're trying to cover way too much territory. The driving scenery in NZ is magnificent but driving is just about all you'll be doing on your itinerary. IMO you would be better off concentrating on one island or the other or flying from Wellington to Queenstown.
We've used lots of the cheap car rental places in NZ and we've never had a bad experience.

I agree with the previous comments. Any particular reason you're spending two nights at Milford? There's nothing there but a cafe, a motel and the boat terminal....and millions of sandflies. It's basically a launching point for the cruise boats and the ending point for those walking the Milford Track. The best of the area is between Te Anau and Milford, not in Milford itself. Lots of walking tracks, etc.

You could easily combine your nights in Te Anau and Milford and get more bang for your valuable time. Te Anau makes a good base from which to explore the entire area - it's about a two hour drive from Milford.

We like APEX for car rebtals.

Thanks for all your suggestions.

My thoughts were that a 300km drive was a piece of cake, at least by Canadian standards. My longest drive I have noted is 329 km so thought that would not be more than 3 to 4 hours driving.

Our goal is to hit the high points in NZ such as the architecture in Napier, beaches in Coromandel, Maori haka dance in Rotorua, museum in Wellington, glaciers, walking tracks in Milford Sound, Mt Cook, etc.

Thanks,

Darren

Just want to point out that the roads in the South Island can be very windy and hilly and can take a lot out of you if you are the sole driver.
I agree that you might be better off concentrating on one island and see it properly...my pick would be the South Island.
Not sure that Rotarua warrants 2 night. If you are only interested in museum in Wellington, perhaps leave early in the morning from Martinborough, drive to Wellington, visit the museum during the day (4-5 hours), then catch the ferry over to the South Island in the evening, overnighting in Picton, hence saving yourself another night. Or alternatively, skip Martinborough, drive from Napier to Wellington and overnight there (we have done this drive comfortably before...the roads are easier on the North Island). Catch the ferry early in the morning and drive to Punakaiki. IMHO there is not much to see in Picton to warrant a stay, it's only a convenient place to overnight to if you are using the ferry.
The Coromandel is beautiful and it would be stunning in January

300km is a piece of cake by Australian standards too, in fact in some places it's a Sunday drive but in NZ, especially in some parts of the South Island, 300 km is a day of driving. Try cutting out a night or two in Te Anau or Milford & give yourself the time to make some road side stops to go 'aahhhhh'.
I understand your desire to see as much as you can. I'm about to do the same sort of whistle stop tour of the US.

Franz Josef to Queenstown is 355 km and will take a good six hours, more with stops.

While 300 km may not be a long way in Canada or Australia, it's a long way in NZ. Roads are narrow and winding, usually one lane in each direction; there are many, many one way bridges and hairpin turns...you just won't be able to drive flat out at 100 km an hour. Your 3-4 hour drive days will take you considerably longer than you might expect. It's not uncommon to encounter sheep and cows on the roadways and landslips that potentally close roads for hours. If you get stuck behind a bus or campervan, or encounter a highway crew, it could take some time to clear.

Add to that the many reasons to stop en route, and you've bascially got yourself a driving holiday. You've left very little wiggle room for contingencies and even less time to explore the places you're driving TO.

If that's how you like to travel so be it, but do be aware that with your current itinerary, the bulk of your time will be spend on the road.

Speediedee, we spent two weeks in the South Island of NZ in Feb-early March of 2012. (Click on our name to see our T/R, Part 4.) We agree with the above posters about the length of time it takes to travel in NZ. Constant driving to destinations leaves little time for enjoyment of the beauty along the way. Wanaka is nice town for a stop between Franz Josef and Queenstown. Happy planning and have a wonderful trip! FYI, we received a lot of helpful tips from Melnq8.