I stayed here this past week. For Diamond recognition, there is free breakfast ($29 per person at the restaurant). There's no club. They have free iced tea and water in the lobby, if they hadn't had that I probably would have requested free waters sent to my room. It seemed like there was a bit of an upgrade but it wasn't extravagant-- just a couple levels up to a nicer room with a patio (not a suite).
The hotel is very beautiful and peaceful, with lots of lush foliage, pretty fountains, and gorgeous 1920s architecture. People who prefer brand-new places probably wouldn't like it, but if you enjoy history and vintage style this is a fantastic hotel.