Hi ladies,
If u r deciding to go to Melbourne, make sure u do not miss out on the Great Ocean Rd (where u see the 12 Apostles) and also Mount Dandenong.
The Great Ocean Rd is SPECTACULAR and takes your breadth away. Try not to join the 1 day tour, as it is very 'rush' and does not allow u to enjoy the sights at your own time. Rent a car and drive up, my and my BF spent 3 days 2 nites driving fr Melbourne to London Bridge and back to Melbourne. Very relaxing and allows u to appreciate the grandeau of the coastline. Prob can do it in 2 days....
Mount Dandenong was very nice too, went there around Oct when the flowers were blooming.... very romantic... also, don't miss out on the wineries.
But depending on the season u go, might hit the rainy season, so be prepared. When I went in Oct, it was raining quite frequently, got drenched at Philip Island standing in the rain waiting for the little penguins to come home!
Don't worry abt navigating around Melbourne, what I did was just to book the flight, first 2 nites accomodation in Melbourne and only took care of the rest when I reached there (e.g. car rental, book tours etc).
All in all, Melbourne was really fun, and u r sure to enjoy yourselves! I myself is thinking of returning there in the near future!