Our suburban block is about 620sqm, not counting the verge, and when we moved in pretty well every part of the garden was covered in grass. Buffalo, couch, kikuyu, we seemed to have a patch of each growing somewhere, not to mention clover and dandelions and various other lawn weeds. It all had to go!
To make this large area grass-free quickly, the option we chose was using a bobcat to remove the top layer of soil to a depth of 10cm. This takes out the grass itself, including the rhizomes growing underground, as well as any grass seeds that are sitting on top of the soil.
The advantage of getting a quick result needs to be weighed against the disadvantage of higher cost and the fact that you will be losing 10cm of your topsoil. If there's nothing but heavy clay underneath (like much of the soil in the Illawarra) this may be quite a price to pay. In our case it was worth it, but we did have to bring in extra soil to cover up the exposed clay subsoil.
Here's what the garden looked like after removing the lawn.
The bobcat was so handy for heavy lifting that we got in a few sandstone rocks to lay around the place and prevent erosion on the steeper slopes. Here they are, waiting to be moved into place. This shot also shows the extra soil brought in to replace the 10cm that had been removed.
Next step, get planting!