Near Melbourne, the You Yangs Park, http://www.parkweb.vic.gov.au/1park_display.cfm?park=208 has some technical stuff, a few shore trails, that kind of stuff, in the Stock Yards area. I got there by train to the nearest train station, and riding out, was about 40 mins ride out. Only a single days ride there, but it was good riding. Kangaroos and wallabies on the trails there which was pretty cool.
Probably not the type of riding you’re looking for, but I did the trail linked below. It’s accessible by public transport from Melbourne (train+bus to Daylesford), and is a (long) day ride, with train back or places to stay at Castlemaine.
http://www.gdt.org.au/trail/diggings/index.html
The first 15km or so is not legal for bikes and had lots of technical bits, the next 15km was easy wide tracks, next 30km was relatively easy singletrack.
In New Zealand, if I were you, I’d go for the S. Island, cos it has proper big mountains, and tons of riding. If Pete VB is in Christchurch still, you should get him to go and do some riding from there. There’s good riding in Christchurch, downhilling that kind of thing, but you can also go to the southern alps and do some proper big rides, I’d totally recommend Craigieburn, but also further s. there is tons of riding (all in the New Zealand Mountain Bike Rides book).
Makara Peak in Wellington was nice, if a bit the same as built trails everywhere else in the world.
One thing is that a lot of the best riding on the S. Island requires some uphill riding and can’t be shuttled at all, for example Craigieburn has 700m of climbing, the Wharfedale Track has something like 800m of climbing, if you’re not into riding uphill at all sticking to one of the cities and riding built trails would make more sense, but you will miss out on the best riding.
The Queen Charlotte Track is really good fun, but there is nothing technical on it, 99% of it is cokerable.
Joe