Help with Southern New Zealand

New Zealand is hard to plan because there are so many choices! Constructing an itinerary takes time. We did 2 weeks on the south island including Queenstown, milford sound (flew back and forth instead of cruising or staying overnight). Did some wine tasting near Queenstown. We then went up to pelorus sound near picton and stayed at an inn only reachable by boat. It was amazing
I will recommend a Facebook group for planning called New Zealand Travel Tips. You can post your itinerary and will get lots of feedback from experienced NZ travelers. Also the woman who runs it will do 1 on 1 consultations if needed. I am not affiliated, but it was so useful for our trip planning.
Good luck!

I’m currently planning 4 weeks in New Zealand and I second suggestion for the New Zealand Travel Tips facebook group if you have facebook.

I understand your dilemma about choosing where to go and how long. I’m struggling with that myself. Good luck to both of us! 😉

Plenty of good info at NZTT on Facebook.
I can give you a bit here although I am no expert.
We visited South Island for 3 weeks late autumn 2024. Just focused on the Southern Alps and Fiordland. I have on a previous trip crossed Cook Strait from the North and visited Picton Kaikoura Christchurch and Dunedin. A good while ago though.
First thing to say is you are visiting Paradise, what ever you do is going to be wonderful.
The hard one on that list is Pancake Rocks. It doesn't fit into your plans.
From Queenstown to Te Anau is a beautiful 2 hours of driving. We spent 3 nights in Te Anau, it was more my style than the busier Queenstown.
We did Doubtful Sound and Milford Sound on consecutive days. Both were day excursions. Both offer overnight cruises though. Doubtful was unanimously voted highlight of our trip by my wife and I. Give it thought. Milford was certainly no let down though. Both were brilliant.
Maybe head back to Queenstown it's no hardship retracing that route. Queenstown to Wanaka. Worth a stop in the cute as a button Arrowtown then the stunning Crown Range, an awesome drive great viewpoints and into Wanaka. From Wanaka we were heading up the West Coast but to do Oamaru you will instead need to head east to Tarras and then north to Omarama. It's a nice little town somewhat famous for it's stunning clay cliffs. It is a straight 120 km run east from Omarama to Oamaru.
Maybe overnight at Oamaru as penguins are usually best seen at dusk.
From Oamaru Maybe straight back to Omarama then onto Twizel. Twizel was our base for our trips into Aoraki Mt Cook NP. The drive from Twizel along Lake Pukaki to the NP is as good as it gets.
From there you can head back to ward Christchurch via pretty Lake Tekapo, Fairlie, Geraldine and Rakaia. Christchurch is a fair sized city very English like. Worth visiting.
It's a straightforward run from Christchurch to Kaikoura. It's been some time but I remember Kaikoura as a beautiful spot.
I think it is another 150 or so kms north to Picton from there.
Pancake Rocks is way over on the West Coast I don't see a practical way to fit it in.

I would add a detour to the Banks Peninsula and specifically Akaroa if possible. It’s worth at least one night, if not two. Nearby Okains Bay has a lovely museum of Māori artifacts.

With 2 weeks I’d build on the west coast adding Abel Tasman and Nelson and skip Christchurch and Kaikoura. The ferry is a 2-1/2 hour drive from Nelson. Make sure to have a ferry reservation.

Minimizing time in Queenstown I think is smart, with traffic and over building it’s awful now.

I loved the activities that I did in Kaikoura. I went swimming with the dolphins which was so fun. You get suited up in a wetsuit and snorkel and they take you out to an area near where the dusky dolphins are swimming. You are told to make noise underwater (e.g., sing into your snorkel). The dolphins are very curious and if they find you interesting they swim closer. It was fascinating to see dolphins swimming around and under me. I also went on an albatross watch; the seabirds were amazing and the albatross are huge. You need to book these activities in advance (there is a strict limit on the number of people who can do the dolphin swim). There is a risk that you won’t be able to go on these activities if the sea is to rough.

https://www.dolphinencounter.co.nz/

If you aren’t interested in the dolphin swim, then I’d probably skip Kaikoura.

If you take the ferry from Picton to Wellington and stay in Wellington, I’d also really recommend the night walk at Zealandia. I loved this walk. https://www.visitzealandia.com/visit/plan-your-visit/tickets-and-tours/

We spent 3 weeks on the South Island in November 2024. I think you will need more than 2 weeks to see and do what you want on the South Island. We did not visit the North Island.

As someone else suggested, if you don't have enough time for the top of the South Island, I would eliminate Pancake Rocks and probably Kaikoura and spend your time in Abel Tasman NP. It's a coastal park and beautiful! Are you wine drinkers? You could do a wine tasting in the Marlborough Region or near Abel Tasman in the Moutere Hills.

I think you should spend 3 nights at Mt Cook in case you have inclement weather, which we did. So we couldn't hike the Hooker Valley Track our first day there. But our second day was glorious with sunshine and blue skies. The HVT hike was one of the highlights of our trip. And if you have 2 days of beautiful weather, there are other hikes you can do at Mt. Cook.

Our itinerary was as follows: (We spent 3 weeks in Australia first, so then we flew from Sydney to Christchurch) - just for context.
Christchurch
Mt. Cook - if you can, stay at Mt. Cook Village. I can recommend Aoraki Court Motel
Queenstown
Te Anau - we added an extra night here at the last minute because our Milford Sound cruise was cancelled and rescheduled to the next day due to bad weather and risk of landslides.
Wanaka
Methven - added literally at the last minute. We had to change our route due to road closures because of landslides. This took us over Arthurs Pass which was stunning.
Franz Joseph
Punakaiki
Kaiteriteri - next to Abel Tasman NP
Picton
Hotel at Christchurch airport for our flight home.

This was for a total of 21 nights. You do have to be flexible in case of road closures or cancelled tours due to landslides.

I just went to New Zealand last October. I joined Red Carpet Tours, which emphasizes on Lord of the Rings filming locations, for 14 days on both North and South Island. The best part is they have arrangements with the land owners of some of the locations, to allow us to go in depth into them, rather than to just pass by them, or just go to the base of them.

On a side note, most members are Lord of the Rings fans, but it's not mandatory.