The climb up to Mt Difficult from Troopers Creek is a tough one, but rewarding. The loop around to Briggs Bluff via Long Point is also beautiful - all a very rewarding walk.
Grampians National Park

The 470m climb up to Mt Difficult, is, um, difficult. The trail follows follows the cliff face up. I guess it is a long, steep climb, which is where the difficulty comes in.
We hiked the circuit out to Long Point and around to Briggs Bluff, then back to Mt Difficult, in one day. It was a long weekend, there were many people out, some doing day walks, others camping overnight.