To the OP curious, you mentioned that the tickets cost $1200 however do you know what the fare class that they were booked into was? Also did the travelers have any DL or SkyTeam status and if so, what level? Since you mentioned citibank card Im guessing that the travelers do not have DL/Amex card?

Reason I ask the above is that Im wondering if those passengers who were rebooked initially onto other flights/routes had one or more of the above. My own experience is that with a higher fare class and/or higher DL/ST status helps to move up the list in case of IROPs.

As to what travelers will be able to get out of DL, make some noise and simplify the story/message as another poster indicated and they will probally get some miles maybe a voucher for the delay. I would not get hopes up too much however for being compensated for late luggage or missing flight on other carrier outside of the itinary, maybe they will get a good surprise from DL though.

-H