At least take a hand winch if you're leaving the gravel.
Stanley is interesting, climb The Nut. If you've got two or more kids they'll enjoy Tasmazia in Sheffield. There's nothing to do in Devonport. Cataract Gorge is worth a visit. Queenstown is creepy, Strahan is nice but you have to arrive there early in the morning or you'll miss all the funtivities. The drive Hobart to Queenstown is gruelling if anyone in your party gets carsick, otherwise it's quite good. Hobart is kind of interesting if you're there for 1-2 days, but apparently the Cadbury Factory has stopped doing tours, a real shame as they were cool.
Once you've done the tourist trail and you know what Tasmania is like, go back in a few years with other 4x4s, mud tyres, winches, and EPIRBs and you'll feel like you're the only people on earth.