Much better value just up the road @ the Sofitel on Collins - rooms typically around AU$250 per night or less if pre-purchased via the Accor website.
GREAT service, one of the flagship hotels for this brand. Immediately opposite a tram stop, and (literally) a 5 minute walk from Parliament railway stations. Great restaurants within staggering distance (including the impressive Collins Kitchen @ the Hyatt).
Superior to the two Hilton properties and the Rialto Intercontinental - the latter of which is at the arse-end of the CBD and significant hike to anything other than office towers and strip clubs. Not that there's anything wrong with that.
The only downside is the lack of a pool (although every room seems to have a decent bath) - but this is a Melbourne thing, even the BRAND new Hilton doesn't have a pool. Seriously, who builds a hotel without a pool? ... is wrong with these people?
Anyway, the CBD swimming centre which has a 50m indoor heated pool is only a 10-15 minute tram/ train trip from the Sofitel.