Dude, I used to live in York. Very dark skies. Drive 45 minutes east from Midland on the Great Eastern Highway. Don't forget to veer off the Great Eastern Highway at The Lakes or you will end up in light polluted Northam. Anywhere along the road between the lakes and York there are large farms with big open fields. Try your luck along there mate. Check out Mount Observation, out that way in the national park too. Google earth can help, along with
http://www.whereis.com/whereis/home.do
Otherwise, head north along the coast up past Yanchep/Mindarie keys to view west, or up the Northern Highway from Middleswan, past the wineries in the Swan valley to get away from Perth's light pollution.
Dont bother heading south as you have to get past Fremantle, Kwinana's industrial lighting, which is HUGE, Rockingham's booming urban lights and Mandurah. Perth is getting BIG.
Hope this helps.
Baz
Barry's home-made observatory
http://members.iinet.net.au/~armstead