I have detected leeway when dealing with a reservationist, even to interpreting the expiry of a promotion to be 11:59pm Hawaiian time. This goes for ticket advance purchase requirements, as well. Also, when I've had the computer "expire me" on a 24-hour book-and-hold, but it was not 11:59pm somewhere in the US, I've called (um, after midnight Central Time) and virtually* always had the reservation honored. Don't know if it was because I was 1K, and/or if it was because there was still room. *I definitely have heard "sorry" when there was no room left, even as a 1K.

I just had this work the other evening, when...

I don't think I saw that my book and hold reservation said anything to the effect that I had to purchase by 11:59pm Central Time -- either when I reserved it, or in the email. When I went in through My Itineraries to purchase, the next evening, it said, in red, just that. It sure wasn't 11:59 PDT yet -- at either end of the itinerary (SFO-LAX) or where I was while purchasing (Marin). I called the .com number, and got the ticket with no problem. No extra fee either. The CSR said that that's a lot of what he does. Interestingly, he was in India.

The points of the anecdote: It appears they're tightening up on Central Time -- in some communications. (I'm not sure it's worth going up on the mountain re consistency here, as I think the advantage still remains with us. Until I get burned a couple of times...) And it's good to keep that united.com number handy.