They may get $90 more from you, but if there was a way to do this, they'd get $531 less from a whole lot of people who also figured it out. You do the math.

As long as they can get $621 from people who will pay that much for a more convenient schedule, that's what they'll charge. Whether or not that's a good business model is a subject for another thread. It's theirs, take it or leave it.

It's your money and your choice. If you have top-level elite status with US, and have access to an elite desk staffed with real professionals (I have no experience with US in this regard) it can't hurt to call them and ask. They may have the flexibility to meet somewhere in the middle, especially if you tell them what your walk-away price is: $91? $300? $620? Short of that, you're SOL. Enjoy AirTran.