Parent's Rooms are like the holy grail of being a parent. A good one can make a shopping trip, a bad one can cause you to wish you never bothered.
I have seen a lot of both. The bad ones are poorly designed (a microwave in between two nappy changing stations anyone?), lacking in basic resources, or worse yet, are just a disabled toilet.
The good ones are well planned, have a designated play area for older children, good feeding facilities and are clean. Above all they must be clean.
I recently went to Melbourne Central and needed a parents room. Rather than look on the map I asked someone and they pointed me to one that wasn't on their mapping system. I felt like I was part of a secret club.
As soon as I walked in the door I was pleased. It smelt clean, was very large and catered to my every need.
If you are in Melbourne and need a change facility, I suggest the Melbourne Central one. It's on the 2nd floor, past the elevators that are near Calvin Kline The same elevators that exit at GAP on the first floor.