The majority of Melbourne suburbs are very safe, especially in relation to the rest of the world. It really depends what YOU want in a suburb. Personally I'd love to live in a place like Hurstbridge but it is out in the sticks and it would a long drive for both myself and my girlfriend to get to work/uni.
So we picked Rosanna in the north-eastern suburbs; its a 5 minute drive to uni for me and nearby to a train line that takes me to work and also near the Eastern Freeway for my girlfriend to get to work. It is also got a supermarkets within walking distance, as well as a couple of nice cafes and restaurants and has the Northland shopping centre nearby, but that's secondary to the convenience of easy travel to uni/work for me and my girlfriend.
Overall, anywhere in the east or north east is pretty decent, but its a got a price tag to match.