The Press Club mentioned in other answers (which are now a few years old) is the flagship of celebrity restauranteur George Calombaris, and was at the forefront of nouveau Greek cuisine. Calombaris was into molecular gastronomy before he was into nouveau Greek, and you could tell: there was tzatziki ice cream to be had.
The Press Club was astonishing in the mid 2000s: every dish a surprise. By the time I last went there, before it closed for refurbishment (and to be shrunk to a third of its size and three times the already inflated prices), it had become a disappointment. I haven’t been to the new place (though I have been to the 2/3 of the restaurant that now serves nouveau Greek street food, trading as Gazi.)
Of the nouveau Greek places, I’d name Hellenic Republic, which Calombaris also runs. It’s not as experimental, but it’s good quality.
I have not checked out the nouveau Cretan place Elyros Restaurant yet. Got to get around to that.
The problem with old school Greek places is that the quality is very often lacking. Especially if they are meat platter joints or tavernas. Most places in Oakleigh, Melbourne’s Greektown, are not to be recommended. (Although at least at Kalimera you’ll get an actual Greek-style souvlaki, and I was impressed by the same owners’ Mykonos taverna.)
There is a hidden jewel in Oakleigh though. Literally hidden: it’s up a flight of stairs around the corner from Eaton Mall; you have to know of it to pop up there.
Mezedakia. Good Greek home cooking, utterly unreconstructed, utterly what mama used to cook, and utterly delicious. No souvlaki platters, and no tzatziki ice cream. Ask for the revani ahead of time. (What is it on Wikipedia? Oh: Basbousa.)