The issue is legacy Marriott/Ritz-Carlton Rewards and legacy SPG were fundamentally different programs.

One was literally about rewards -- points for "free" stays. The other was about recognition with some customers "preferred" over other customers.

We really won't know the true direction the new, unified program is going until January, when the new name is revealed. However, up until now, it has been a case study on how not to combine loyalty programs for other airline and hotel companies.

Marriott likely never will officially tell us what the upgrade priority will be since that precludes Marriott's ability to tweak it and not be liable whenever one of us gets peeved for some perceived slight!

Of course, the simplest answer is almost always the correct answer. Not surprisingly, our friend @frenchft already has heard information about upgrade priority that I now have also heard from GMs at StR, RC, Luxury Collection, and W properties:

Bolding mine. Makes a lot of sense to me, and that's pretty much reinforced by what i've heard from other GMs and senior managers in the know.

(1) Plat Premier Ambassador returning guest
(2) Plat Premier Ambassador
(3) Plat returning guest
(4) Plat Premier 75
(5) Plat 50

Sounds so reasonable and obvious, doesn't it?

I'm sure @C17PSGR will want to elucidate how exactly anyone might know that one is Ambassador status, because the how seems most important to @C17PSGR. Go right ahead. I don't much care how the hotel knows my Ambassador status, only that the hotels does know my Ambassador status. Whether the hotel recognizes my status because of some code at the front desk or because of an automated list every day or because of a call or email my Ambassador makes to the hotel, I could care less.

For those of us coming from SPG, anything that Marriott does that better recognizes you as Plat Premier or Plat Premier with Ambassador is an improvement. So there shouldn't be any complaints.

For those of us coming from Marriott or RC, anything that Marriott does that better recognizes you as Plat Premier or Plat Premier with Ambassador is an improvement, as well. So there also shouldn't be any complaints.

In short. the new Marriott program sounds like it will provide better recognition of status than either of its Marriott Rewards or SPG predecessors. The IT may not yet be in place to affect that change, but it's coming. I've heard November for the SPG properties. I don't know when the Marriott properties will see the changes. But we already know they're coming.

Ironically, everyone at all of the brands--even at RC and Marriott--all colloquially referred to PlatPremier with Ambassador as "Ambassador status" anyway. Even the above post by @frenchft reinforces this. So those worrying about the clumsiness of the name don't need to bother. I'm sure Marriott wanted to stay consistent with Platinums (which includes everyone with more than 50 nights now) and just as consistent with Platinum Premiers (which includes everyone with more than 75 nights now). Referring to Ambassador guests officially as Platinum Premier with Ambassador is just mimicking the clumsy marketing approach that SPG did, as well.

Granted loyalty status should provide some priority, but I'm of the mind that ANY returning guest, especially frequently, will bump anyone regardless of status. Repeat customers are much more valuable than a first time status customer. Remember, it's who you know not what you know.

I'm sure that a very frequent (higher revenue or VIP) guest with no status otherwise probably still would be treated much like an Ambassador guest or Ambassador returning guest.

We must always remember the context with which these points are raised. I'm sure that when @frenchft asked, it was with an eye towards people with status. I did the same when I asked. So the answers we get are provided in that context. It doesn't mean that there can't be slight adjustments for special circumstances or for other conditions about which we didn't think to ask.

So when the Obamas visit the St Regis San Francisco, even with no Marriott status, I'm sure they'll be upgraded even more than I usually am! :D

That being said, when most returning guests with no status visit the St Regis San Francisco, and I'm there at the same time as a returning Ambassador guest, I usually would expect I am given even better upgrade priority--and I always have been.

Please also consider that most times, as an Ambassador guest, I usually am upgraded to the nicest room category and usually a suite (for those hotels that have them in any decent quantity) WELL BEFORE MY ARRIVAL. This is something that almost all legacy SPG hotels in the luxury and upscale categories did for me as a routine matter of course. (Note that the Sheraton New York Times Square did not, however!)

As an example, I already am upgraded from an entry level room to the specialty SLS Suite at the SLS Beverly Hills next month. I was upgraded weeks in advance to a specialty Metropolitan Suite at the StR San Francisco a few weeks ago.

Whether the legacy Marriott brands will do the same remains to be seen. Most legacy Marriott brands do not have as many suites as many of their legacy SPG counterparts, so the apples to oranges issue is sure to arise. I did get pre-upgraded before the Aug 18 merge in May at the RC Kyoto to a specialty suite, allegedly because I was Ambassador status and also as a service recovery for poor concierge service before my stay. I have upcoming stays at the RC San Francisco, RC Dallas, JW Austin, and RC Coconut Grove to see how they might handle me.

I can think of a resort in Florida where just about anybody would have a higher upgrade chance than the Obamas. (joking for those that think this was political).

Or the Trump Turnberry, actually. Fortunately, I don't think we have to worry about either scenario arising too often!

I do think their might be something valid about the 5 point order-of-upgrade matrix being suggested in this thread. My hotel of choice has very few suites and I've been upgraded on 15 of my last 21 nights (4 stays in total).

Probably because he visited during a campaign year. There are so many Plain Jane hotels in Iowa, New Hampshire and South Carolina that get all sorts of political VIPs, including presidents, every four or eight years. Some of these politicians basically live at these hotels while they're running for presidents.