Cairns is probably the best bet this time of year, and if you have a look on the graphs (follow the link at the top of the page) you'll see it indeed has a good SE tradewind forecast. It's about 2500km from Sydney.
Melbourne has some wind forecast, but it's a Northerly, I don't know if there's any spots they kite there on a Northerly, on an open beach that would be offshore. That's just 870 km from Sydney if you take the shortcut.
The same gradient off the high cell off Sydney is predicted to throw a similar, if not a bit lighter, Northerly across the Eastern end of the South Australian coast, that's about 1400km away from you.
Otherwise we have a half decent front passing over Perth on Friday, should throw some wind up on Saturday. We're just 3900km from Sydney, if you take the back streets.
Around Sydney itself doesn't look so good for this weekend, I'd say due to the proximity of the high cell centre. Have a look at the forecast synoptics here, it's only got up to Friday right now though:
www.bom.gov.au/products/IDG00073.shtml . The same charts come up if you click the 7 day forecast chart for any state.
