When in Melbourne,
Vue de Monde.
55th floor of the Rialto Building. The Rialto used to be the tallest building in Melbourne, but since the much taller Eureka Tower went up in 2006 nobody cares about the Rialto any more so they converted their old observation deck into a restaurant.
Consistently rated as one of Australia's best restaurants. $150 for a four-course meal, or $250 for the ten-course degustation. Haven't been there myself yet, but I'm actively looking for an excuse.
Come to think of it, there's a restaurant in the Eureka Tower too, it's called Eureka 89 and is on the 89th floor. Higher than Vue de Monde, but
much less favourably reviewed. Cheaper though. But if you want cheap food and a good view, pack a sandwich and head for the observation deck.