If you already have the Platinum, the Gold really does start to feel redundant unless you’re getting outsized value from dining points. Using the Resy credit and the monthly Uber, Grubhub, and Dunkin credits before canceling is exactly the right move.
There’s no true no fee downgrade path from Gold. You can’t product change it to something free like you can with some Chase cards. Cancellation is usually the only clean option unless you want to keep it open just for credit history.
Retention offers are hit or miss. Sometimes they throw points or a partial statement credit, sometimes nothing. If they offer something close to the annual fee, great. If not, canceling is reasonable.
As long as you cancel within 30 days of the fee posting, you should get the annual fee refunded. Sounds like you’ve thought it through.
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