When I call the 800 number, a real human being picks up right away and helps me. If I'd like to catch an earlier or later flight, if it's within 24 hours, I can usually make the change with no charge. I use this perk dozens of times a year, and it even enables me to book cheaper flights because I'll usually be able to make adjustments on the day of travel. If I end up on the standby list, I'm put at the top (because it goes in order of highest status before first come first served). If I use miles to book a flight, I can cancel or change the flight at any time. This lets me speculatively book a vacation flight to Maui months ahead of time when availability is good, even if I'm not sure I'll be free then. My entire family gets free bags and free extra legroom seats when they travel with me. I get to sit in fancy lounges when traveling overseas. And the first class upgrades are a nice bonus.