A couple of additional points:

the self check-in kiosks recognise status and the baggage tag that is printed has a black coloured 'premium' logo printed on it.

The AirNZ website provide good information on domestic *G lounges (known as Koru Clubs or KC) - although the *G aspects aren't so obvious as KC information. Similarly for 'Space+' seating allocated based on a combination of fare class and status.