Western Australia vs Tasmania - anyone?

Tom and I are thinking about a small domestic trip next Easter (maybe this is a travel hangover from South America??)

I wanted to go to Uluru but Tom has seen it already so not really keen to go again.  He suggested Margaret River/Perth or Tasmania.  To be honest I don't know much about either so I'm hoping you can give me some advice.  We'd like a reasonably relaxing holiday - not too packed but not just sitting around doing nothing for 5 days.

Has anyone been to either and can make me a recommendation?

Thanks in advance :)

Oh PS is anyone NOT sick at the moment?  I've been sniffling/coughing/congested since last Tuesday.  Not fun.