The amphitheatre would be nice, however it would also result in extremely high scalping prices again because of the limited seating. At least with the ACC the secondary market prices would be almost affordable.
And boy oh boy, if it does happen to fall in September, I hope it's not the week of the 11th-17th. I've got:
Sun: Pearl Jam
Mon: U2
Tue: Pearl Jam
Wed: U2
Fri: U2
Sat U2
It would be pretty funny if Thursday turned out to be Coldplay!