Moderator, Marriott Bonvoy & FlyerTalk Evangelist
Join Date: Oct 2002
Location: McKinney, TX, USA
Programs: United Silver; AA Plat/2MM; Marriott LT Titanium; Hilton Gold
Posts: 11,775
The room guarantee doesn't apply to the upgraded room. You can turn down the upgrade to keep your originally reserved room. Now if they tell you they don't have one available, then you might have a case on the room type guarantee.