Book domestic Y at schedule open with a crappy schedule for very cheap and wait for schedule change 3-4 months out. I'm in school so I know my schedule way ahead of time and I can fly transcon Y for 8-10k points OW on what is otherwise easily a 200-300 OW ticket even with sufficient advance purchase (and sometimes even more). And the schedule change window leaves time to book a cash flight if needed. Also great for tickets I want easy refundability on. Last minute Y tickets can also be a great value.