As a diamond, I used it to see where I'd be upgraded to, and ended up in very 70s-style split-level suite on the 9th and 10th floors with a spiral interior staircase. I've only seen a room like this in one other Hyatt, the one in Vancouver B.C.
My impression from previous stays in Rosemont is that suites there are just two connecting rooms with one made into a parlor.