I can totally recomend staying at Marlene & Martys Place. Actually I just stayed with Marlene for 16 days while Marty was working outside Australia.
We get along very well during my stay. I traveled by myself and so I just enjoyed the chance to have a nice chat when I want to or spent time alone when I want that.
You can easyly discover the city from the area by foot or bike (two rental stations just around the corner). I often went to the south melbourne market - a "small", nice market with a lots of things to discover ( I had a haircut, massages, food, drinks and a lot of very nice chats).
I did a Barista course in the capital of coffee (baristacoursemelbourne 4h/69AUD) :) and made my way to Fitzroy (nice streetart, nice cafés, restaurants and wine shops (Wine Republic offers free tastings on fridays).
I can recomend a wine tasting in Yarra Valley (4 wineries and a lunch) with the australian wine tasting company (120 AUD/8h).
So stay with Marlene and you'll have a very open minded, friendly and caring host. She experienced living in other cultures and knows about how it feels to be new somewhere. If morning or evening or in between the both, she will always gives you a smile :) that's always the best start.