Far from any beaten path, Western Australia is truly one of the more remote destinations on the planet, and holds a wide range of adventure. Most of the towns are in the southwest portion of WA. If you spend some time around Perth, be sure and check out the old port town of Fremantle (locals call it Freo) for some "culture". As far as climbing is concerned, the majority of development has occurred around the Perth area, since it is the center of population (80% of W.A.s folks live in this area). You can find granite boulders in abundance in the Perth hills, offering a mixture of sport and trad lines. There are many areas around, but the ones with the most routes are Churchman's Brook and Pinjarra. The Darlington Boulders also have a plethora of fun things on which to play. You find the granite sea cliffs of Willybrup farther south around the Margaret River area, as well as vineyard country for the wine connoisseurs. If you're in the Pemberton area, check out the Gloucester Tree for an interesting excursion. Farther inland to the southeast you find the Stirling Range with some longer multi-pitch routes on Bluff Knoll up to about 300m. There are also some peaks to bag in this area (Toolbrunup Peak has the best views) and bouldering is everywhere. Heading north you really get into the outback and inhabited areas become few and far between. Kalbarri is a picturesque coastal town with nearby Kalbarri National Park which offers coastal cliffs, gorges, and magical coves. Z-bend gorge has routes up to about 160m in length, both hard sport and trad lines can be found here. Still farther north, where the outback meets the Indian Ocean, you can boulder right on the beach at Coral Bay and do some cragging north of Learmonth in Cape Range National Park.
A good source of information for climbing out here is the Climber's Association of Western Australia, (CAWA)
It's very expensive to fly from eastern Australia to Western Australia because very few people do that. A trip to Australia should probably be planned to visit either the east or the west. Trying to fit both in a trip will require a month or more. Routing through Singapore is likely to be cheaper. Believe it or not it was actually less expensive from Denver to fly through London and Singapore than it was to head west. This was something like 28 hours in the air, but saved a lot of money.
By the way, just because a gas pump is green in color does not mean that it pumps diesel gasoline. Most of the good rentals take diesel. This has life-threatening potential if you're in the middle of nowhere, because a diesel will run for a number of miles on regular gas before it craps out on you.