Steve,
There are some places not too far out of town that you can get to that are good and dark, my dark site of choice currently is up at the car park of the Lake Mountain Ski Resort, others go to places like Kinglake, Snake Valley, or just head out of the city and find and open spot somewhere.
I quite enjoy packing up some snacks and drinks and taking a short road trip... nice and peaceful away from the kids for an evening.
Geoff.