outside Auckland NZ - itinerary help

It seems you have very specific interests. Strikes me as lots of driving missing the obvious, but perhaps that is your preference. I easily spent multiple days in Auckland and Rotorua exploring in and around the towns. But, this isn't my trip.

Rotorua has sights in town, but also surrounding area. Geothermal areas like Waimangu Volcanic Valley, several Maori attractions, hiking, thermal and mud baths.

Glowworm caves are an unusual feature of New Zealand. Take a look here, this is a popular attraction. There are other cave attractions as well. https://www.waitomo.com/glowworms-and-caves/waitomo-glowworm-caves

The Coromandel Peninsula has some interesting sites, if you haven't looked into it. https://www.newzealand.com/us/coromandel/

I second the suggestion about going to one of the Waitomo glowworm caves - it was a truly magical experience. And being a LOTR fan, I loved the visit to Hobbiton. Truly amazing to see how well preserved all the hobbit home exteriors are. Enjoy your trip and you'll realize that you need way more time (or a return visit) to see such an interesting country,

Another vote for the Waitomo glow worm caves. And Rotorua is a must. Wish you had more time.

You will want to prebook Hobbiton.
You cannot do it independently you must go on the organised tour.
Your 2d day in Rotorua may be limited by the timing of your Hobbiton tour. It is about an hour from Rotorua to Hobbiton.
Your planned drive to Rotorua will take you at least 3 hours so you will have a limited time there. Is Rotorua a must visit for you?
Hamilton is not a particularly exciting place maybe look for an alternative. We spent the day and night before visiting Hobbiton in beautiful little Te Aroha.
The idea of visiting Waitomo Caves seems good in theory but I don't see how you can fit it into your plans.

Itinerary C.
Day 1. Arrive 12.35 am.
Daytime pickup rental car after breakfast. Drive to Helensville (45+- mins) check out filming locations. Drive onto Warkworth (45+- mins) do the same.
Drive back to Auckland (45+- mins). Spend the afternoon at the War Memorial Museum. Stay the night in Auckland.
Day 2. Drive to Hobbiton from Auckland for pre booked late morning tour. After tour drive the hour or so to Rotorua. Visit pre selected sight in afternoon and perhaps an evening activity. Stay the night in Rotorua.
Day 3. Morning visit to another sight in Rotorua. In the afternoon drive to Waitomo stay the night in Waitomo.
Day 4. Do prebooked Waitomo Cave tour in the morning. In the afternoon drive back to Auckland Stay the night in Auckland.
Day 5. Drop off rental car check in at airport.

^^^^^ This one makes sense to me for the short time you have available.

Personal experience, I was stunned that my first and second lodging choices in Waitomo were booked full 4 - 5 months in advance.

Our recent North Island trip was done by campervan so I am not much help when it comes to hotel type lodging.

Otorohanga might be a better choice for hootel accommodation than Waitomo. We camped there, it is a decent sized town not too far from Waitomo.
We visited the little Kiwi House there too. Not sure that will fit into the plan though.

@eatsrootsandleaves - thanks for itinerary C -- this does seem to work better.

For all -- when I wrote Rotorua, I was mistakenly thinking that this was the area where the glowworm caves were. I've since re-educated myself. In Rotorua area, we're considering geothermals near Wai-O-Tapu (Lake Ngakoro Waterfall and Lady Knox Geyser).

I know it doesn't quite follow itinerary C, however a new question is whether it is possible to do Hobbiton & the glowworm caves in the same day? We're considering the shorter tour without the extras for the glowworm caves. Yes, we will prebook Hobbiton & the glowworm cave tours.

Again, thank you all for helping refine our itinerary. It's still a work in progress yet it is starting to come together.

Waitomo is about 80 to 90 minutes drive from Hobbiton so it would be doable. I believe commercial tour companies do both on the same day.

Wai-O-Tapu is about 25 to 30 minutes outside Rotorua on the Taupo Road. To get there you will drive past the beautiful Rainbow Mountain, excellent hiking option if you had time. Also you will drive past the turn off to a "hidden gem favourite" from our trip in Kerosene Creek.

We were low budgeting so didn't visit either Wai-O-Tapu or Waitomo Caves on our recent trip. We have visited them years ago.
We did to a free glow-worm cave on our own north of Auckland which was a bit special.

There are day tours (very popular) from Auckland that do Hobbiton in the AM, then Waitomo after lunch. I'm sure you can do both in one day with a car and starting closer than Auckland. Google maps says 1 hour 17 minutes between them. Both have required tours - just schedule carefully.