So, I took a later flight a few months back in exchange for a $750 travel voucher from American. Holy crap, they could not make this thing any harder to cash in if they tried. You can't use it to book a flight online. You can call in but your reservation is not confirmed until after you mail it in and they've received the voucher. Apparently, the only 1 stop way of using this thing is to go to an American ticket desk at an airport. I tried to use it while at the Admiral's Club at O'Hare once and was told they didn't have time to handle it and I would need to go back through security to the ticketing counter. What a pain in the ass.
If Delta would match my status and give me access to their lounges I would probably switch.