Air NZ Business Premier is very nice, same seat as Virgin Atlantic Upper Class which can be made fully flat and they'll also add matress, duvet and pillow so you can sleep properly. Very decent inflight service as well.
PVG-AKL-SYD wouldn't be a huge detour IMO.

Singapore Airlines is of course always a good option if you can find award availability.

Otherwise have you considered OZ via ICN? That would actually be the shortest route, shorter than both PVG-BKK-SYD and PVG-SIN-SYD.