Returning from Perth is a lot easier on the body clock than going there - though most of the difference was due to a civilised start time (3am is not a good time to start your day), and a shorter transit time in Sydney. We were at Perth Airport at 8.30, and had a second breakfast about 9.45, before our flight left at 10.15am. (We decided not to buy food on board our Virgin Blue flights, as the quality is pretty ordinary and the choice is limited.)
The flight to Sydney was fairly crowded, but it went smoothly and we landed at 2.15pm Perth time, or 4.15pm Sydney time. The 2½ hours before the flight to Christchurch passed quickly; the transit to the international terminal and other arrangements took up the first hour, then we spent about 30 minutes in the duty free shop, followed by a nice Asian stir-fry meal at one of the airport cafes.
The next flight was less crowded, and we watched some TV show videos on my laptop, read and snoozed, and were in Christchurch just on midnight local time. Our Perth body clocks said that was 8pm, and we were through customs and home in fairly good nick, though still a bit weary from the travelling, at 1.30am NZ time.
The temperature change was expected, but still rather extreme - we have gone from 27oC in Perth, to 21oC in Sydney, to a rainy 4oC in Christchurch!