Originally Posted by qasr
1K members can do it online with the "Book and Hold" button. If you aren't a 1K then you can call and hold a reservation, but they will charge you the ($5?) ticketing fee.
Actually, anyone can use the "book and hold" feature, not just 1Ks. I've used it many times as a 1P, 2P, and lowly MP member. The key is having a fare that will allow the "book and hold" feature.
Many of UA's cheapest fares require that they are ticketed immediately. On those fares, you will not be given a "book and hold" option. Others require that you ticket within 1 day.. or longer. And on those fares you CAN "book and hold" until midnight the following day.
From what I've heard, 1Ks get this feature regardless of the fare type... but I can't confirm that.
In any case... try to book it online (and avoid the $5 phone/$10 in person fee).