We had a great time at the Park Hyatt. We stayed in an extra large "club room". The room was indeed big, to the point where we couldnt actually see the TV while sitting on the bed! This was a bit of a pain as the couch in front of the TV was really uncomfortable. The bathroom was massive too, which isnt actually that useful, so wouldn't pay for the extra-sized room again. The "Club" itself was nice - great aperitifs, snacks and breakfast, and fantastic, helpful and friendly staff. Nice views out to the MCG and the top end of town.
Pool was lovely, room service good, bath excellent. Nothing to complain about really apart from the decor - quite dated.
Its a nice hotel, with prices to match - not sure its the best value around Melbourne.