melbourne to sydney

My husband and I are a u.k. couple in our 60,s visiting Australia in late Feb for 5 weeks, staying in Melbourne for 4 days then renting a car, first travelling to Warnambool then into the shipwreck coast for a couple of days then onto Sydney for a further 7 days, we have three weeks to make the journey and will stop at motels and B&Bs along the way. Any help you can give with regard to places of interest etc would be greatly appreciated, thanks a lot Stokesy