You should not listen to the Aus commentators specially Chappel. I'll say it again, you neede no more then 20 more overs to roll over us and THAT cost you the test despite after a day lost. Pretty sure if we had a cloudy days play you would have been in trouble with the ball moving around in those conditions.
We were scoring quickly at the end of day 4 and early day 5. If we'd declared earlier we would have had to bat again anyway. I think it was a better choice to keep batting whilst the runs were coming easily.
I think Australia needed at least another session to be in a position to force a result. We would have still run out of time if we'd declared sooner.