Been meaning to report back for sometime now. In a nutshell, it worked, and it worked well. Some thoughts - they prefer you to charge everything to your room, and shortly after checkout, all your multiple and many tier credits post to your account. That wouldn't have worked for me for a couple reasons. 1) I was eating at restaurants and using an Uber Visa credit card, which rebates me 4%, so charging those meals to my room would have essentially cost me money (that same credit card only rebates 3% for hotel charges). And 2), I wanted to see a running total of my tier credits the entire time I was trying to pull this off. So, I was making multiple-trips-a-day to the Mlife booth at a couple casinos. The most important thing I leaned is that the Mlife customer service clerks who work at the booths have a LOT (and I cannot emphasize that word enough) of discretion when it comes to what they can do for you. Just for one, my last night in town, hours after I checked out (I was planning on driving home later that same night), I was perhaps $80 spend SHORT of what I needed to get to Platinum before I left town, and it was close to midnight. All the Mlife booths close at midnight. I was explaining my dilemma to an Mlife clerk whom I had previously gotten friendly with. Not a whole lot of ways to quickly spend $80 late at night, (I wasn't hungry, I had no interest in gambling at that time, and even if I did, those gambling credits take some time to post, and I really wanted to leave town WITH my new Platinum card), midnight was rapidly approaching in any event, and I'm leaving town imminently as well. It wasn't crucial that I get the Platinum card right then; I was so close I would have gotten it during my next trip (I had until 9/30/18 to get over the 200,000 tier credit hump), but since this trip was a 3X special promotion, if I hadn't gotten it right then, whatever spend was left, would have cost me three-times-as-much, if I had left it until the next trip. Thankfully, the Mlife desk employee understood the situation perfectly. He told me "go get a coffee at Starbucks and bring me the receipt." Remember again, I'm about $80 short! I did what he said, and he obviously gave me credit for at least $80...because he said "you made it"...and he printed out my new Platinum card, about 10 minutes before the Mlife desk closed. He got a big tip for that. Best "$80" cup of coffee I ever had! And that was only the second nicest thing an Mlife desk employee did for me on that trip. A female clerk at another property did an even bigger favor for me. She got a generous tip from me.....and a dozen roses. Bottom line...be nice to those Mlife clerks, they can be EXTREMELY helpful.

My new Mlife Platinum card has an expiration date of 9/30/19. Pretty cool. (You always get at least one-full-year whenever you move up a tier, and Mlife expiration dates are always on 9/30.) Of course, all my current (200,000+) tier credits expire this coming September 30, but I'm optimistic they'll run that 3X promotion again....and I'll take advantage of it again. I read about someone who was offered it last February. Also, I received this e-mail 10 days ago:

<<M life Rewards members are invited to earn 2X Tier Credits for the following experiences NOW through July 31st: Hotel Accommodations at Park MGM•Dining at Primrose, Bavette's Steakhouse & Bar, Moneyline Sports Bar & Book, and Double Barrel Roadhouse•Entertainment at Juniper Cocktail Lounge>>

That would be 50 tier credits, per dollar, for non-gaming spending if I took advantage of it, but I have no reason to now. However it does seem to show that they, not-infrequently, run these cool tier-credit-promotions. They do seem to be targeted though.

Long-story short....I'm glad I did this. Please let me know if you have any questions.