The American Express Business Platinum card comes with a $200 Dell credit twice per year. A reader sent in a tip that they made a Dell charge immediately before closing the card. The Dell credit posted a few days after the account was closed. Good to keep in mind for when the timing is tight.
I’d guess the same would hold true for the airline incidental credit or the wireless credit. And similar for the Saks credit on the personal Platinum card. Hopefully others will chime in below with their experiences on these and other credits.