Any recommendations?
Do a search on this forum for 'New Zealand guidebook'. There have been several threads with lots of suggestions. If you have trouble with the search function, here's a link to the list of threads.
Looks like Lonely Planet is recommended.
I purchased the Fodor’s and Lonely Planet NZ guides and checked out all of the NZ guides available at our local library, but unfortunately did not find any guides comparable to Rick Steves’ guides.
However, I have heard that the NZ Frenzy guides by Scott Cook are very good.
I mostly used websites, including YouTube and Pinterest, to plan our NZ trips. Below are some websites I found helpful.
https://www.tripadvisor.com/ShowForum-g255104-i125-New_Zealand.html
https://www.newzealand.com/us/things-to-do/
https://www.aa.co.nz/travel/accommodation/search/new-zealand/all/
https://www.dangerous-business.com/destinations/new-zealand/
http://www.earthtrekkers.com/new-zealand-travel-guide/
https://www.neverendingfootsteps.com/category/destinations/oceania/new-zealand/
https://www.nomadicmatt.com/travel-guides/new-zealand-travel-tips/
https://youngadventuress.com/category/new-zealand-2
http://www.stokedforsaturday.com/category/destination/new-zealand/