We found the 86 and 96 trams to be very convenient in the CBD. Trams within the designated CBD are free. Melbourne streets have some inclines in the CBD, so the tram eliminates some hills. Not all tram plaforms in the CBD are accessible, (most are). 

For the 86, there is an accessible platform for 86 from the Docklands are on Harbour Side Quay near the La Trobe Street Corner. Many trams stop here, the 86 was the only accessible one that stopped here.   All the platforms up Bourke Street for the 86 are accessible. The platforms outside Southern Cross Station are accessible.  The closest platform to the Southern Cross Station for the 86 is the first stop on Bourke Street (southern end) near the Spencer Street corner. 

For the 96, we caught this on Bourke Street near the Spencer St corner and travelled all the way to St Kilda.  There is also an accessible stop outside the Casino for the 96, but this stop is just outside the free tram zone. From the Casino stop you can walk / powerchair to South Wharf for cool restuarants and the DFO outlet store (right across from The Lume - see separate entry).  

There are two apps you could try to mke your travel smooth in Melbourne - "Public Transport Victoria " app and "tramTRACKER"  .