Thanks for all of the Dubai advice - we traveled NCL-DXB-AKL on 30th Dec in Business - with a 10 hour layover: what we learned was that anything 10+ hours you can use Dubai Connect to get a hotel on Emirates.
We knew about it in advance, but was given a voucher at NCL alongside all of the boarding cards - just needed to swap it once in DXB and got a 20-minute trip to the Marriott - really nice for a few hours sleep, shower and then back to the airport at your convenience.

We used concourse B for the outbound (about 3 hours used to get breakfast and settle) and then briefly on the return yesterday to stretch the legs and grab some random bites. Was relatively busy, but plenty of space for seats/work space etc.

Only downside to the whole trip was Emirates cancelled the return leg due to the immense flooding in Auckland last Friday - but left us entirely in the dark and scrambling to find our own accommodation/return leg.....natural disaster aside, given we flew Business we did expect better customer service from them though - has made me re-think whom to spend my money with next time - shame, flights, lounge and service on-board was above the level I had hoped for!