What thatbum said for the southern suburbs. On the northern side you would have a few options eg Woodlands, Carine, Duncraig, Hamersley, Warwick, and further north. Basically, the older suburbs with still reasonable sized houses (not McMansions) and at least circa 700sqm blocks and therefore a decent amount of outside play space for kids. Hard to see how such a social ecosystem can develop with big houses on postage stamp blocks a la all the new suburbs lately.
But I also agree with Depreciator - a lot of it is luck and staying in the one spot long enough to form established links into that community. One problem in Australian communities is that it can take a long time to establish a social network for kids and families in each community. If people are new to a community where everyone already has a trusted social network that is already working for them it can be very hard to break in. Takes a long time... of staying in the one spot to find the right friends. Letting kids ride their bikes to friends places etc requires finding the right group of friends within a reasonably small radius.
With young kids / toddlers we have found playgroup and similar resources useful for getting to know people. For older kids, there are sports clubs and other activities to link into. I think it's really important to get out there and meet people at these kinds of activities in order to establish social opportunities for kids.