Different with every airline, I think. I have done the *Alliance thing, and had to call back every day, until finally an agent got a supervisor, and they held it until a day after I was allowed to book for the return. Guess you just need to get the right agent who "knows" how to make the computer hold it.

I think some airline, Delta maybe, will hold anything for 30 days?

I am going to try to book Delta paid flight and upgrade with minimum points (50Krt) and get more miles for future flights, as I still don't have enough points for a ticket!