I'm envious; Perth and environs may be my favorite place on the planet.

But, the city of Perth proper is about 20km inland on the banks of the Swan River. If you want something near the beach or on the beach by the Indian Ocean, you'll want to look for places in places like Cottesloe or Fremantle. There are a number of nice places to stay in Freo and elsewhere along the coast.

A good overview site is: www.perthtouristcentre.com.au

If this isn't a work trip, or if you have a few days free to holiday at the beach, I'd strongly suggest taking a ferry over to Rottnest Island and either staying in a rental cabin or taking a hotel room. The island has a variety of lodgings from hostel-caliber to luxe. My personal choice on past stays has been the Rottnest Hotel (or "quokka arms") for a moderate level hotel that's right on the beach.

The official Rottnest Island site is: www.rottnest.wa.gov.au for an overview of the island and links.