In my experience, the upgrade you receive is property-centric and has little to do with your having booked a Senior rate. I am just concluding a stay at the Panamá Marriott, where I was assigned their Master Suite, having booked a basic room with a very lucrative Senior rate. The FDA referred to it as their "best room." Perhaps Mr. Mahasa and/or others who have extensively used this rate could share their experiences. I've been using this rate whenever it makes sense over the past X years, and have never been penalized, in any way, for having done so.