It was either channa or slippahs who made a comment earlier this week about threads being posted about once a day regarding certain topics. Standby definitely qualifies for it!

Matt, you can do a search on the board and find more info than you ever thought possible regarding standby rules, etc.

To answer your question - you can ask in MCI to be placed on the standby list for the earlier MSP-SEA flight. However, they may tell you to wait until you get to MSP as the gate-agent has to do it up there.

Also, your standby is only valid for the originally booked class of service. You will lose your EUA (if you get one for your originally scheduled flight). After you clear the standby list on the flight, you will have to try to clear the EUA again for the earlier MSP-SEA flight.

-RM