I now have to actually pay for my flights , (wasn't that a shock to the system!) and I generally fly cattle class.
These days I wouldn't bother with business class unless you need to impress, premier economy is fine.
Its not like first class in the old days, then there was a difference. There still is with the other majors. Not so much now with Air NZ. When the Purser does his tour of business class with his sleeves rolled up (literally) no tie, saying "Gday great to see yer!" you know standards have dropped.
In case you didnt know you can buy access to the lounge I think its $40 for 4 hours and $80 for all day. If you are stuck at the airport all day its well worth it.