We cruised the NZ fjordlands in 2013 on Celebrity Solstice 12 Night Auckland to Sydney. Of the 12 days, we spent one day visiting Dusky, Doubtful, and Milford Sounds (fjords). It was a very enjoyable cruise, stopping at many ports in NZ and Tasmania in Australia. The fjords were one day of a 12 night cruise.
Here are the photos from the NZ part. The fjordland pictures are at the end, all taken from the ship.
https://bhughes.smugmug.com/Travel/Tahiti-New-Zealand-Sydney-2013/New-Zealand-Nov-2013
In 2023, we are booked on the Island Princess 16 night "Land of the Midnight Sun & Summer Solstice"
https://www.princess.com/search-cruise/details/?voyageCode=2310
This cruise visits Songefjord (Skjolden), Norfjord (Olden), and Romsdalsfjord (Andalsnes), on three different days, with a port stop in each one. Look at Skjolden on Google Maps. It is located 200 km from the ocean - that's a really long fjord. The fjords are three days of a 16 night cruise.
For both of these cruises, we booked aft balcony cabins. I recommend this for both the NZ or Norway cruise. The aft location allows you to be on you balcony while cruising through the fjords, while sheltered from the wind. A normal balcony, on the sides, would have a lot of wind chill