I would not plan to fly standby; I’ve had to before, because of weather and flight cancellations, and it makes flying, which is already one of the most unpleasant ways of travelling, even less pleasant. Because you’re flying standby, you are automatically flagged for extra security screening, and there’s no guarantee that you’ll get where you want to go—and if it’s a multiple-leg flight, you might get stuck in an airport (or in an expensive airport hotel) overnight. You might save $50 to $100 over what you’d pay if you booked a good fare in advance; you’ll more than make up for it in hassle, uncertainty, stress, and annoyance.