By bus
Regular coach services travel between Sydney and Brisbane via Byron Bay.
By train
Trains no longer stop next to the Railway Hotel. You can transfer to a coach from the train at Casino. You can buy a through ticket. Casino is located quite a distance from Byron Bay and it might often be best to get a bus directly to Byron, saving a lot of trouble. Or, if you are lucky enough most of the domestic airlines have sales on pretty consistently from most major cities to the Gold Coast, Brisbane and less frequently Ballina. All of these are closer than Casino and may be cheaper if you find the right sale.
By car
Byron is around 9 hours drive from Sydney. A good days drive, with many possibilities to stop and rest. Traffic on the Pacific Highway gets busy during school holiday periods. Avoid traffic delays entering Byron from the Ewingsdale Pacific Highway exit. Take the Pacific Highway Lennox Head exit at Ross Lane and enter Byron from the south.
Byron is only just over an hour from the Gold Coast, and just over two hours from Brisbane.