Does Marriott Plat benefit apply on Ritz-Carlton?

Unfortunately not.

In a word, no. When you check-in you can always mention that you are a Marriott Plat, but don't expect much, if anything extra.

Thanks imverge & hhoope01.

I rarely stay at RC if I'm paying (or the company is paying). It's just too fancy for an ordinary business trip. But on holiday, it's a different story, as we have time to enjoy all the benefits and luxuries. My pattern lately has been earn=Marriott, redeem=Ritz. As a PLT MR, I've never received any sort of recognition or upgrade while staying at RC, although their service has always been superb, of course. Once on holiday in Seoul, I paid for a stay at the RC, and booked the Club level. It's very nice, with several (5?) different food presentations per day. I was torn between sightseeing all day and going back to the hotel to take advantage of the afternoon tea and cocktail hour offerings in the lounge.

When redeeming MR points at RC, I have yet to figure out how to get upgraded to the Club level (or even how to pay for the upgrade), but since my partner and I tend to stay out all day, we'd probably only take advantage of the breakfast, and I don't think the cost of two breakfasts in the restaurant would be as much as the upgrade. So we end up on the lower floors with 'the little people' as Leona Helmsley would say. Although, once again, at RC, there really are no 'little people'. (And in Tokyo, there are no lower floors)

FWIW, I'm sure regular RC guests turn up their noses at those of us staying on MR points, but, for me, it's one of the best benefits of the program.

Just ask at the front desk. I recently stayed at the Cayman RC which was very nice as well. I asked about a possible upgrade when I checked-in. They mentioned that if I was willing to pay, I could upgrade to a club-room or even an ocean-front room. In fact, the manager took the time to actually show my wife and I exactly which room we could upgrade to if we so chose to do so. The view was awesome, but given that we weren't spending a bunch of time in the room, it just didn't make sense to pay the extra $100 or so per night.

I also use my MR points exclusively at Ritz Carltons....it is how I choose to live and it is worth it fully to me. Now while I don't get a benefit of an upgrade for being a MR Plt, since I am a very frequent repeat visitor to the ones in the Caribbean the Ritz will usually always upgrade me to the Club level even though I am staying on points. That is the service I love about the Ritz.

I have also had success asking at check-in about an upgrade fee. I have been successful more often than not and every time, the upgrade has been $100 per night. Since this is usually less than the website difference between club and non-club, it's worth asking.
As for the value, there is absolutely no question, IMHO, that club is almost always worth it, even at the published rates. With two in the room, you really only have to do breakfast and a couple of drinks in the evening to make up the difference. If you have a day or two where you're just hanging at the pool, you can easily eat every meal there and save a bundle.