Realistically, you are looking at a min of 3 hours for commute to the airport, check-in, flight time and travel form airport to city from anywhere to Sydney or Melbourne. So that means a very early start to the day to make a 9am meeting, and a late arrival home following a 5pm finish. Yes it can be done, but its going to get you down eventually.

However, it is better than commuting through most US airports. At least you get food of some sort at those times of day even on the 1 hour flights.

Generally the only way to get any decent discounts on QF flights is to be part of an organisation that spends lots of money with them, or just buy the cheap red-e-deals off the net. The discounts for large spends are normally on the flexible fares, so the internet specials are still cheaper but don't have the flexibility.

Might be better to live somewhere outside Sydney (say Blue Mountains) and commute by train. Certainly cheaper!