Originally Posted by BDL-FRA

I've had pretty good luck in getting SWUs to work with S fares, but never never never in advance. It only seems to work on a standy basis at the airport, and only at the discretion of the GA. Still, I've been unsucessful only once when trying (at check in with a relatively inexperienced agent), and I didn't bother trying again at the gate as I was with someone else and already had a great seat in E+. I wish they would make this policy official, as it seems to be a win-win situation for all involved, especially when they are going to need to op-up someone anyways.