I had my 50th stay here recently.
The standard Plat upgrade (subject to availability) is an Exec Suite. This has occurred in all of this years stays except my last where I turned down 1124 to get 1517 which is a corner Exec Room-Park View, larger, but not a suite. This is one of my favourite rooms here. Rooms XX24 are typically Exec suites with a Park view .
The Hotel does typically do a good job of looking after Plats. Some staff, like at all Starwood properties,still need to be directed that a Platinum upgrade,where available, is to the best available room (including Exec Suites at the SOTP) and not to the next room category.
The SOTP will ,IMHO,upgrade to suites more often than the Westin.