Absolutely agree, SYD-PER-MEL is the better way to go SYD-MEL, nice flight and well worth doing even if only having a spare day (there is a red-eye from PER-MEL at midnight so you could even do this at the expense of a hotel stay but a bit rough with the short flying time). PER is such an interesting place (more interesting south of perth) and a contrast to sydney and melbourne.
Edited to add since we are doing city analogies that MEL is San Francisco.