I enjoyed (not sure if that's the word..) the staircase spur of Mt Bogong and I know we obviously won't have any climb that length, but surely there must be some good climbs that are 20%+ gradient for 2 or 3 kms at least?
Around Adelaide I know of the Pengana (Not sure on name) Track at waterfall gully, which is quite steep but also quite short. Also a few sections of Mt Lofty which are moderately steep.
St Marys Peak from memory is mostly pretty flat until the last 1.5km or so? You start from a fairly high plain so there isn't as much elevation gain as you'd expect.
The Mt Cavern walk in MRNP was surprisingly steep, especially if you went up from the creek side. There were parts there 30%+ and I reckon would average over 25% from the creek to summit.
More suggestions please, I love doing new walks I haven't seen before
