And, to answer your question, there is a Marriott Ambassador program and some of us have them (I have a nice metal charter member card too
). Unlike the SPG program, its not clear what the criteria is to have an Ambassador. We know its not assigned to the needy who look for help a lot (see another thread). I am a multi-year Plat Premier, LT Plat, and would certainly meet the SPG Ambassador requirement. On the other hand, I believe some here were appointed Ambassador's at a lower level.
All that being said, I'm not sure whether our Ambassador's work a lot of magic but maybe I'm not asking for the right thing. I presume the hotel concierge/GM would certainly want to help. That being said, when I looked at options for Marriott hotels in Paris for a possible quick trip, I didn't get any strong recommendations from my fellow Marriotters that there was a "great" place to stay on the Marriott side. I'd look for that thread if you're trying to pick a place.