My partner and I were in Perth this past New Year. It was our second visit to Perth. We like the casual vibe of the city and plan to visit again in a couple of years.
This visit we stayed at the Medina Executive Barrack Plaza...it is extremely well located for Northbridge, Court Hotel and gay scene, downtown shopping, as well as being just steps from a full service grocery store, and the main Perth train station. It's a serviced apartment hotel...not 5* luxury, but very comfortable. We paid $165AUD for a Premier 1 bedroom apartment.
Many of the larger chain hotels have less convenient locations that require 20+ minute walks to get downtown or to Northbridge.
A visit to Rottnest Island off Fremantle is certainly worth a day-trip.