I've actually used the PF Chang's option four times in the last month. Flying AA, it was actually pretty simple to enter at TBIT now they have Pre-Check. I headed upstairs, had lunch/dinner at PF Chang's and then walked over to T4 for my flights.
I can get a decent amount of food for the $30 credit. You check in at the hostess station (have yet to be asked for a boarding pass) and they scan your card and present you with a receipt/voucher. You can choose the dining room or the bar - the latter is faster. Then you give your server voucher and you're all done.
Just remember to use a separate form of payment to tip your server!