I have Biz Plat, I have not even asked for a retention offer, but I have gotten:
Dell semi-annual credit up to $200 twice a year (I use the basic $200, half for Microsoft 365 and half for warranty), $20/mo toward my wireless bill, $20/mo shipping credit (didn't know about this, alas, until last month, but USPS is included so I can just buy $20 worth of stamps), and also got a $200 "Fee Discount." So maybe that "Fee Discount" (which posted close to to the time of the AF) was my "retention bonus."
All things considered not too bad, although I lament the loss of AA gift cards available under the Fee Credit.