I am thinking of using an award BOS-SFO-BOS for Sep. 26/29. Unfortunately, there are no award seats for Sep. 29, so they offered me SFO-BOS on Sep. 30.

Will I be able to stand-by in SFO for a flight on Sep. 29 (space available, of course)?

Thanks!

My answer is yes. My friend was on an award ticket over in Europe early august of this year and they let her stand by to come back a few days earlier, when there weren't anymore Miles seats. She got home with no problems.

It helps if you are travelling alone (no need to hope for 2 seats) and have no luggage (helps persuade them).

Don't try this on a US Airways/Qantas award. You can beg all you want. QF won't budge.

Since you are staying over a Sat night, you should be fine. It should be noted that the least expensive US awards require a Sat night stay, otherwise the mileage required are 2x as much. My mother uses the award for BUF-PHL rt in the same day 2x a year, in the past someone on this forum (sorry I forgot who it was) posted that you can do back to back ticketing for both trips.