Hi from Perth
Should you miss the West Coast altogether you asked....
Perth is a very relaxed city, are there many attractions here as such though? We have the beautiful Kings Park which is massive public park/native bush reserve perched atop a hill overlooking our CBD. It also has a very elegant war memorial and is a beautiful spot to have an evening picnic overlooking sunset in Perth.
The city of Fremantle sits on the harbour and is filled with old buildings, buskers, markets and the cappuccino strip of cafes. Or you can have fish and chips at one of the purpose built restaurants on the waterfront. The Fremantle Prison tour is excellent apparently though I've never been.
I love Rottnest Island a short ferry trip off the coast. The island is vehicle free so you hire bikes to get about on. The island is also home to Quokkas a small rat/kangaroo cross kinda of marsupial. Accommodation can be cheap here.
The whole coast is filled with fabulous beaches often with cafes to watch the gorgeous western sunset on.
I also love the Busselton/Dunsborough area down south (about 2-3 hours away) Busselton has a jetty with a little train and an aquarium at the end of it. Dunsborough has lots of cafes and little shops - we're staying 2 nights down here in a fortnight I can't wait!
Nearby is Margaret River which is the hub of our wine region and boasts and excellent chocolate factory.
I've not been too far north but skip Kalbarri, we went there last year and it was like a tourist town that everyone deserted 10 years ago. Not a lot open anymore (as in places to eat) and thin on attractions.
I'm originally from NZ so my travels around the rest of Oz are relatively non existent yet but hope this gives you some insight to the west
