SPG Platinum 100+ night Ambassador member here, averaging 130-140 nights per year and (due to SPG Pro business group bookings in addition to my personal bookings) probably $100K in annual spend towards SPG. I'm only SPG Lifetime Gold but would have been Lifetime Platinum in 3 years. (So close, and yet so far.)

I'm at 85 nights already on 42 stays for 2016, mostly at W, Westin, Le Meridien, and Sheraton...with several StR and Luxury Collection, plus a few Four Points thrown in. By the end of June, I'll be over 100 nights.

I just stayed 6 nights in late April at the StR Bora Bora--where I was upgraded from a deluxe overwater villa on a 3rd party auction booking at 50% discount to the Royal Overwater Villa with private pool. That upgrade was all about my Ambassador.

I can tell you that I (and likely all Ambassador level SPG Platinum members) are looking on with extreme interest as to what Marriott offers for its Elite Concierge members. There seems to be some diversity as to how impressed people can be with their SPG Ambassador--ranging from people like me, who think my Ambasaador is phenomenal and provides me outstanding Aman/Four Seasons levels of service and benefits at even the best SPG StR and LC and W properties...to others who seem to barely notice that they have an Ambasaador (based on comments here on FT in our respective threads).

My impression for Ambasaadors is that those guests staying at more full service to luxury properties ultimately will benefit most--since those are the properties that can offer the most. I believe that SPG members who most often stay at cheaper upscale-midscale brands like Sheraton, Four Points, Aloft, and Element are least likely to experience massive improvements in hotel experience. Considering those are the lowest thresholds of SPG hotels, it might make Marriott elites cautious who stay at comparable brands like Courtyard, Residence, SprongHill, and AC hotels or even lower brand categories such as
Protea, Fairfield, TownePlace, and Moxy.

That is no guarantee that Marriott wil operate Elite Concierge as SPG operates Ambasadors, of course. But with SPG having higher brand categories overall and having higher revenue customers than Marriott, it would stand to reason that Marriott ultimately will have Elite Concierge provide more benefit and value to those staying in the luxury and upper upscale brands. For Marriott, that includes Ritz Carlton, JW Marriott, Edition, and Bulgari in luxury and Autograph, Marriott, Marriott Executive Apartment, Renaissance, and Gaylord in upper upscale.

I'll be curious to hear what experiences you get with Elite Concierge. I can say that we SPG Ambassador members are hopeful, since Marriott obviously is trying to demonstrate a comparable benefit for us in order to keep us loyal when the programs finally merge in 2018.