A paid business class return LHR-AKL on NZ pretty much got there for our family in style and comfort a couple of years back. We paid about £2700 each back then, about 5.6p per status mile.
When LX offered their cheap intra-Europe business class fares I think these earned at around 4p per status mile for e.g. MAN-ZRH-ATH return. They dropped this fare offer a few months back.
Fare classes A on US or UA can still earn well, e.g. SMF-PHX-TPA at £513 costs 3.5p per mile.