midnightsociety2 One of the reasons why these schools give such tight turnaround times for your decision is because they're trying to steal away the best applicants from each other before they know they're in anywhere else. So they're totally used to dealing with requests like this. For that reason, I tend to try to stay pretty concise and factual with my emails. You're right, they don't need to hear that they're totally your top choice, etc., even if it's true. If you do have a clear, succinct reason why Austin is #1, it would be fine to mention it briefly. But other than that, I opted for something along the lines of...
"Dear XXX,
I am writing to let you know that I have been admitted to XXX program and have been asked to give them an acceptance decision by XXX date. I would appreciate anything you may be able to do to accommodate an earlier admissions decision.
Sincerely yours,
Vmacc"
Basically, I try to use wording that makes it clear that I understand that I'm asking something of them, and that I understand that they might not be able to do it. That I'm not so presumptuous to assume that they can or would work their schedules around my needs. Feel free to borrow whatever you language you like from the above example.