Melbourne to Tasmania
Traveling from Melbourne to Tasmania has a few options: the Spirit of Tasmania overnight ship, flying into Launceston, or flying into Hobart.
The Spirit of Tasmania travels across the Bass Straight and typically takes about 11 hours to get from Melbourne to Devonport, a small city on the north coast of Tasmania (about an hour drive from Launceston). This trip is usually done overnight, where you can book accommodation ranging from a glorified recliner to a private deluxe cabin. Cars can be brought on the ship for additional fees, and the cost of a one way ticket across for one person (sans car) can be anywhere from about $120 to $460 depending on how much luxury you want and what time of year you're traveling. There are also day tickets available that are a bit cheaper than the overnight tickets, but require killing an entire day at sea. Food and drink is also not included in the fare, though there are restaurants, eateries, and bars available for patronage aboard the ships.
The latter two options are a bit quicker: a flight from Melbourne to Launceston is just over an hour long, and to Hobart is under an 1.5 hours. This is certainly the easiest way to go if you're short on time or just don't have the patience for a long boat ride. Also, with some of the low-cost airlines that have recently opened up in Australia, the price can be very competitive, and often actually cheaper, to fly to Tassie from the mainland. The two main low-cost airlines that fly these routes are Tiger Airways and Jet Star. Other airlines fly to Tasmania (Quantas, Virgin Blue, etc), but the rates will typically be far more expensive than the two companies previously mentioned.
On our trip, we were excited to use Tiger Airways for the first time. We had seen fares to Tas for as low as $30 one way and were hoping for a good deal. Unfortunately, we waited too long to book our peak season tickets and ended up taking Jet Star on the way there and Tiger on the way back to get the best rates possible. We spent AUD$250 each round trip for the tickets which we booked about a month and a half in advance. My recommendation: book early for the best prices!
There are many ways to traverse this relatively small island (avg approx 250km wide x 300km tall on a map) but the most private and self-satisfying way is to rent a car and drive yourself around. There are buses, trains, planes and ferries, but they all come on a schedule, pick up and drop off at predetermined destinations and require you to share your vacation with others. This might be exactly what you want and in most cases will likely end up costing less than renting a car or camper van. But, you'll have to look into that yourself because we booked a car and drove all around the place!
We made a loop that covered most of the main areas of Tasmania and drove a very leisurely schedule of approx 2000km in 10 days. We could have certainly done more and, obviously, could have done less, but our schedule made for a good pace and only required an average of a couple hours of driving each day. The speed limits on the roads in Tasmania were rather generous on the highway (110kpm/75mph) and rather slow through the towns (50kph/30mph), but we never had a problem and always felt safe. The roads are well kept and are sealed (paved) most places you need/want to go, unless you're heading to the very rural south-west forests for some serious hiking. Most rental car companies have it in their contract that you are not allowed to drive their normal cars (non-4wd) on unsealed roads, but the Europcar employee specifically mentioned that certain types of damage caused by driving on unsealed roads is not covered in the damage waiver, which implied that driving on unsealed roads is expected, if not allowed.
Like all Australians, Tasmanians drive on the left side of the road. Since moving abroad, my partner and I have not found this to be a problem at all; you just need to turn off your auto-pilot and pay attention to the side of the road you're on. It has not been a big deal for us, but if you're wary, there are plenty of tours, buses, and trains available for travel around Tasmania.
Note: Spirit of Tasmania photo from http://www.spiritoftasmania.com.au/