I was up your way a year ago and sailed a racing
yacht from Adelaide to Geelong. Back Stairs Passage
is an interesting area also. The best time to sail to Tassie is of course the summer months. What you really have to do is focus on the weather
prior to departure and wait for a big fat high and make a run for it. From your direction I would do it in stages. Adelaide - King Island - Flinders Island and then down the East Coast
to Hobart. Or if your adventurous, King Island check the weather
again and make a run for it down the West Coast
. Either way is very interesting. Yet, another option, King Island, Stanley, Wynyard, Beauty Point (Launceston) and then around Banks Straight and South. This can be done pretty much in day trips. If your willing to wait a couple of years you can catch up with the around Tassie Rally. One has just been completed and the next one is in early 2013. You can join up at any point along the route
. Just remember, the weather is the key component. Hope that helps.