Don't take your experience with RI's as typical since they have a lot of 1 & 2 BR's to upgrade to and generally bend over backwards to accommodate. CY's are the dog of the Marriott system with regards to upgrades and a few other things IME. The above advice is all good regarding Marriott, Rens, JW, etc (full service). It's going to be a pleasant surprise at best and takes some pre arrival and on site work to make it happen, far from guaranteed even at the highest elite level.