Hi Wendy, I have been upgraded and a fantastic one at that. I had a "free" room booked for my family of 4 at the Sheraton Maui. I assumed we would be stuck in the back of the hotel. They upgraded us to an oceanfront Ohana(family) suite. Sweet! Another time, I was at a Sheraton in Providence R.I. - not an upgrade, but there was a letter welcoming me as a corporate preferrred member along with a tray of water, cookies and fruit(complementary). These 2 events caused me to think that this corporate preferred status might have some weight over regular preferred.