Many international air fares are still cheaper now than they have been for a number of years, due to the GEC. The chances of them still being that cheap by next year for one of the high seasons (ie northern hemisphere summer, our winter) I reckon are pretty slight. And seats at that time will get hard to come by if you leave it late.
Qantas SYD-BKK-SYD is around $1441 now, $999 next month, and $1441 again for July 2011.
That is unless the situation in Thailand deteriorates again, and the Aust Gov issues another 'do not travel' advisory. Knowing that Thailand's troubles are still basically unresolved, that's quite possible. On the other hand, your chances of getting in trouble in Thailand even if things do deteriorate in the same way again is pretty slim. Savvy people in BKK last time just avoided the small trouble areas. And outside BKK there was no trouble.
Of course if you want to fly through SIN, flights from here to there won't be affected by what may be happening in Thailand.
But if you're thinking Singapore airlines (ie via SIN), it may or may not be cheaper to grab a low cost airline to Thailand from/to SIN, especially since you're flying out of different Thai ports. Altho make sure you pay enough for your likely luggage weight upfront.
As mjm056 says, Jetstar's starclass may be worth a look ... never tried them but they do seem to come on sale often ... but still seem to end up a bit more than econ fare with a full service airline.