As much as possible, although I don't have too much time these days. I love the atmosphere - especially around the cultural precinct on weekends as there always seems to be something interesting happening.
I go every few months. I love it there! Mostly I go during the school holidays and take the kids as there as the City Of Perth runs some great free holiday programs. I also like to go to Kakulas Brothers to buy my spices, dried fruit and nuts there.
I did go to Perth, a long time ago, to visit friends for a week, who'd moved there from Harare, Zimbabwe. They lived outside Perth, but I can't remember where they lived now. so I guess I went into Perth CBD while I was there visiting! Then another day about 5 years ago, we were in Perth, while visiting Fremantle on a cruise right around Australia. (We caught a train up there.)