We had the same dilemma when we first moved over with job offers in Perth and Brisbane. We went for Brisbane for many of the reasons mentioned by others on this post and have not regretted it, its a great lifestyle for us and our two young children. I haven't been to Perth and so can't comment, I have heard it is very beautiful but isolated.
We do see lots of geckos, spiders and creepy crawlies, not sure how that compares to Perth, although when hubby worked over there on one site he did comment on there being far more flies during particular times of the year.
I suppose you have to weigh up what needs you have for your family in terms of entertainment/lifestyle etc Hope you get lots more advice to help with your decision.