I stay at the Sheraton Wall Centre regularly so here is my take: The Club level is in the south (old) tower. The nicest standard rooms are the corner rooms in the North Tower, especially when you get a higher floor where the views are beautiful.
I personally prefer the north tower because the ventilation system is better (it always seems stuffy in the south tower even though you can open the tiny windows) and because it feels more "laid back" with a large, open lobby and a sort of different design to the rooms.
anyhow, thats my 2¢