I stayed at the Westin Melbourne about 18 months ago for around a week. It is a good hotel. No question. That said, it was a somewhat surreal experience for a number of reasons.
First, it was a week before the season began and a few weeks before the Australian Open tennis event. I would describe this as the calm before the storm where everyone is charged up but no one has arrived, yet! Second, I spent most of the time either working with the Concierge to get on Royal Melbourne or playing said course along side Kingston Heath (both are absolute musts!). Third, hanging out around St. Kilda. Fourth, let's not talk about Brunswick street.
The infrastructure for the hotel itself is rather bland. I'd say this is exactly because the hotel shares its premises with luxury apartments. No hotel 'buzz' just a lot of subdued activities of normal life intermingled with hotel life such as sharing the elevator after checking in with someone carrying groceries home for the evening.
One thing is certain. The staff
are excellent as are all the staff at every SPG property I've visited in Australia. But each property is also unique, which may or may not be to your personal taste.