Hi,
NZ does have sleeper seats on one or two of their newer 747-400 services. Usually AKL/LAX/LHR. But I have no idea how you locate them.
Despite that servive is very very good in first class, but I probaby would not pay the extra, and I agree without guranteed sleepers it is not in the same league as the othr airlines. Use points instead and make your own mind up.
Mark