Hi, I booked a 2 bedroom apartment at the Seasons Botanic Gardens in Southbank/South Melbourne. It's on St. Kilda Road, and is about a 10 minute walk to AAMI stadium through the Botanic Gardens, and about a $9 or $10 Uber to Federation Square (Transport Bar) and/or the CBD.
I stayed there last weekend, and if you have Twitter there are pictures of my room (a 1 bedroom apartment version) on the "#BardysWorldTour" feed. The rooms are very flash and comfortable.
The 2 bedroom apartment sleeps 4 (2 in each room). I think you can get 2 King size beds and/or 1 king and 2 singles. It includes bedrooms, kithchen, bathroom, lounge with couch and arm chairs and dining table, flat screen TV and a balcony.
I used booking.com and got 4 nights (for up to 4 people) for AUD$992. That works out at AUD58 each per night.
I thought that was pretty good value.
There are HEAPS of hotels in the CBD. Check out somewhere like booking.com - anywhere inside the rectangle bounded by Spencer St, Flinders St, La Trobe St. and Spring St. will be great. South Yarra near the Botanic Gardens is also good - I find it quieter but still really handy by tram, Uber or walk.