Thanks for the very detailed response. So if I check in on the web for the 7pm, and get to the airport at 1pm hoping for the 3pm flight, you're saying they'll push me on the 3pm at the counter, right away? What if there's only a few seats left on the flight? Will they confirm me that early, or will they make me sweat it out until a few minutes before boarding?

Agreed about riding in coach for the early flight. ITN shows P9 F5 for my original flight, but P6 F1 for the standby (along with only Y4...)