I would say, what can you afford? If you can afford PE it is better than economy. If you're not sure if it's good enough value, consider:
+how well you can sleep in economy class--since both flights are overnights
+whether you want to be able to do whatever you want (work, sleep, eat, watch media) without having to worry about the persons in front or behind you?
+are you a "get me off this thing ASAP" traveller?
+are there any value-extra seats (bulkhead or similar), where even a $100 surcharge will get you much more leg room (though the TV screen will be in the arm of your seat, making it slightly more narrow)?
I'm short (1,68m) and normally can sleep in Y class with a bit of chemical assistance. But the PE experience on AKL YVR is excellent. It is NOT business class; it is much nicer than economy. But I can sometimes upgrade using my status upgrades.
Definitely the non-stop flight is worth up to $400 extra each away, to avoid LAX and US immigration crap.