Thanks.. SO many places to research now..

I am still undecided as whether to do WA and SA in the one trip or break it up and do it over 2 holidays..

What we like is this.. Family orientated activities, museums. Not really into the theme park type things just yet.

Love beach walks and mountain walking.. lots of nature things. Love scenery

Hope that helps
Def go Rottnest then (cant half tell i love the place, and im a person who hates the beach usually so thats saying alot!!)
they have lots of tours for families, bike riding/lots of walks where u can discover the quokkas and great hidden beaches, everyones so laid back its awesome!