So I was playing around with this again and I've pulled off some spectacular things.
1. Wanted to Fly BOS-FLL, Cheapest Flight was on Providence-PBI. Booked that and then Same day changed for $0. (Can do It online) to BOS-FLL. Saved a TON of money.
2. But now I'm thinking bigger! Hidden City. JBLU posts some ridiculous routing that are Super $$ that I would never book. Tomorrow I'm Flying BOS-DCA(Service at IAD has been cut) when I go to "change flight" what do I see?
My BOS-DCA flight was $65 so BOS to MCO for $65 would be nice. (Note I ONLY Book 1-ways on JBLU) since they are easier to rebook when fares drop. This might be too far though...