"University of Pennsylvania's Marriott code 4309 is an academic institutional code. No FlyerTalk thread discusses UPenn verification incidents. University institutional codes at Philadelphia-area Marriott properties are familiar and unchallenged. Academic travel patterns (conferences, academic visits, faculty stays) are the lowest-scrutiny category at Marriott full-service and select-service properties."

"GAP Inc's Marriott code GAP is listed in corporate code databases. No verification incidents documented in FlyerTalk or Reddit discussions. Clothing retail corporate codes at Marriott receive minimal attention from front desk staff — retail employee IDs are not standardized enough to be reliably verified. US domestic properties rarely verify retail-sector codes."

"In North America I've been asked a single time in the 15 years I've been using Corp rates (for a few years I'd use them on multiple stays per week). My trick is to approach the counter in a friendly way, ask how they are doing, maybe ask an easy question about the hotel (where's the gym?) and connect with them (boy it's hot out there today!) They are happy to have met you, it is a pleasant experience, and you go on your merry way. I'm also Titanium for life and currently have Ambassador, but I've done this when Gold and Platinum. For that one time they asked I said I had actually just started and didn't have my business cards yet, but should have them for my next stay and they let it go. I was never asked by that hotel again (Courtyard Bellevue on an Accenture rate.) Doing a mobile check-in will also shorten the time spent. Just have your ID and card ready to speed things along."