Technically, the published benefit isn't for a suite upgrade, but rather for the "best available room." As described in the official SPG statement of Platinum benefits, such upgrades are subject to several conditions and limitations:

That's right. Legitimate reasons for getting no upgrade of any kind include

• You booked your stay "through a pre-paid third-party channel" such as Priceline.
• You're at an all-suite hotel.
• You're at an Aloft or Element hotel.

No.

First of all, the benefit covers only Standard Suites. As the published benefit statement makes clear, "Specialty Suites such as, but not limited to, premium view, Presidential, Honeymoon, and multiple bedroom suites are excluded."

Second, the benefit is "[s]ubject to availability at check-in." If an otherwise qualifying suite (or other room) is not "available" at the time you check in, you're not entitled to it.

Why might a suite be available for a paid booking right now, for tonight, but not "available" for purposes of upgrade? Lots of reasons, including

• it's before 4pm local time, and some Platinum (or other elite) SPG member is taking advantage of the separate late-checkout benefit. So the suite will indeed be up for grabs to any willing purchaser later today--and is thus listed in online inventory--but right now is occupied.
• the suite is empty, but hasn't yet been made ready by housekeeping.

Additionally, even if a Standard Suite is cleaned, ready for occupancy, and available for booking online, you're not necessarily entitled to it, because it must be available "for the entire length of the stay." If you're staying at the property for 4 nights, you can't just look at rooms/suites available for tonight; a suite open right now might be booked for tomorrow night or the night after that. In that case, you can't have it, even for a portion of your stay.

Finally, properties often pre-block suites and upgraded rooms for elite status guests ahead of time. These rooms are still offered for sale, and you can change your reservation to pay for the suite. But it's not considered "available" for you to be put in at time of check-in. SPG provides properties with a suggested order of priority for elite members. So the suite that you see may be already be pre-assigned to another elite guest with a higher "priority" than you.

Yes and no.

Yes, in the sense that you as a guest are in no position to determine whether there's a suite occupied by someone checking out late and/or being cleaned by hotel staff. And no, in the sense that these things can in fact be determined after the fact by somebody who is not you.

First, what not to do: make a scene at the front desk waving around your laptop opened to the SPG site showing suites available for booking. As you know -- you read items 2-4 above, right? -- that information is at best evidence that there might be a suite available for you.

If you think you're being short-changed,

• Ask politely for an explanation.
• If the clerk's answer suggests a fundamental misunderstanding -- for example, a bogus excuse such as "this Sheraton doesn't offer that benefit" -- ask to speak to the manager.
• If no manager is available, s/he refuses to speak to you, or the answer seems contrived/confused/deceptive, resist the urge to be a DYKWIA. Take the room offered and contact SPG corporate -- ideally, one of the FT Lurkers -- for assistance. Unlike you, they can determine if a property's manager is confused, lying, or both, and fix the problem if indeed you have been wronged.

Perhaps. Properties are entirely free to go above and beyond the published program benefits for Platinum guests (or even lowly Golds), but this is not the same as an entitlement. It's bad for a property to overpromise and underdeliver, and you may well choose to take such concerns to SPG corporate representatives. Just keep in mind the difference between a clear entitlement under SPG's terms and an extra offer on which the hotel couldn't or wouldn't follow through.