I am Australian and traveling on an Australian Passport, too. My current ESTA expires in September 2015 My 90 day VWP will be up at the end of June. I have spent the whole 90 days in both AZ and OR ...
I'll be looking to base myself in Vancouver soon. In the past, you've always had to prove at the border that you'll be leaving again, one way or another. Last time they didn't take the "I'm planning ...