Originally Posted by
milaohu
I have a partial answer for "close in" ticketing.
AV lifemiles can't see a UA award ticket that is 7 hours later, while UA/AC can see it.
Not necessarily true. I have ticketed UA less than 2 hours from departure on LM.
OP - Its a risky bet. If its a simple trip (like 1 segment) and you have used your LM account before and know that your cc wont flag it as a foreign transaction etc, you can book LM close-in. If you are stuck in ticketing, you are doomed though. Cancellation is painful, but possible.