I can now confirm that those upgrades days before arrival happen without SNAs. I actually had requested an upgrade with SNAs, but already 6 days before arrival I got bumped up to a St Regis suite without taking the SNA that I've subsequently cancelled back into my account.
St Regis suite is in essence just a much larger room with a massive bathroom. The Ocean Suites are more proper 2-room suites with much more outdoor space as well.
Platinum Breakfast is full breakfast!