I had a quick 2-night stay in St.Regis Bangkok which was good and I will consider coming back in the future, although it was not overly positive to the point that I will start ignoring other excellent alternative hotels in the city.  

Location

The location of the hotel is excellent because it is centrally located, it has direct access to a BTS station on the Silom line, and it’s only one stop from the Sukhumvit line.  I personally prefer to stay in a hotel on the Sukhumvit line, but the Silom line is good to visit temples because you do not need to transfer to reach Saphan Taksin station.  One of the best spots is probably to be at the intersection of both BTS lines which would be Grand Hyatt or Renaissance, but anyway the difference is very small (only 5 min walk) so comparing those locations would be splitting hair.  

Room

I booked the basic room and got upgraded one category to a Grand Deluxe room; standard suites were not available online at time of check-in so I did not expect it.  Based on feedback from others here, in terms of upgrades Platinums can be upgraded to suites when available so that would be similar to Sheraton Grande Sukhumvit in the sense that the hotel upgrades when possible but the issue is the limited number of suites which makes it not the easiest property for suite upgrades.  I believe SGS and St.Regis are better than Athenee who is the stingiest of the three: I have occasionally not received upgrades even when room categories below suites were available, so if I cannot get a modest upgrade then in my experience it is not very likely that I would get upgraded a suite when booking at Athenee, available or not.  It’s not necessarily a deal killer but I keep it in mind when booking.  

The Grand Deluxe room at St.Regis is not very different than the Deluxe room, but it’s a bit larger.  I have stayed at 7 of the 10 Starwood hotels in Bangkok in the last couple of years (only missing the W, 4P, and Aloft) and in my experience I would say if you don’t get an upgrade because of high occupancy (or only a minor upgrade), the St.Regis has the best room I have seen within Starwood options in Bangkok. The size is excellent and the room was in better condition than I expected based on some comments on FT regarding construction being of low quality and already deteriorating despite the hotel being only 7 years old.  The room at St.Regis is somewhat nicer and larger than Athenee; the room at St.Regis is significantly better than the basic room at Sheraton Grande Sukhumvit which is not to say that rooms are subpar at SGS. I especially liked the extra space in the bathroom at St.Regis and the shower of St.Regis is in better shape than the aging one at SGS.  I was surprised to find Elemis amenities instead of the standard Remède amenities found in other St.Regis hotels, perhaps because it costs less to get a room at St.Regis Bangkok than other St.Regis properties.  

If there was one minor odd issue in the room it is that the DVD player was not connected to the TV and upon inspection I realized that it was not possible to connect to the TV which is why staff never did it. They must have replaced the TV recently and the TV only has an HDMI connection, and not the analog inputs, while it’s the other way around for the DVD player.  It’s not a big deal because I guess not many guests will care for watching DVDs in Bangkok, but staff should have done something about it if they want to be thorough.  

Dining

Breakfast was good but clearly a notch below the two Luxury Collection options in Bangkok (Athenee and Sheraton Grande Sukhumvit); this is unfortunate, it should be the other way around.  Choice at St.Regis is nice but I found it better at Athenee in part because the latter has more choices of fish dishes and Indian dishes.  Fruit selection is more varied at SGS, in particular I enjoy mangoes there.  St.Regis had a decent fried rice option but not as unique as the more specialty ones at Athenee such as fried rice made with raspberry rice which is healthier, or if we venture out of Starwood, the crab fried rice which I enjoy at Grand Hyatt. Also the curry chicken at St.Regis had pieces of chicken which were not of the highest quality, clearly below competitors noted above.  On the two mornings we had breakfast, the dishes were different, but only marginally so. For example one day there was green curry with chicken and another dish was red curry with vegetables.  The next day it was red curry with chicken and the other dish was green curry with vegetables.  So technically different yes, but they could be a bit more creative. The fried rice and cold salads were slightly different too but not much.  I found other hotels to vary their offerings more than St.Regis did so if I was on a longer stay for example 5-7 nights, it might influence my choice of hotel a bit more.   

Regarding drinks, Prosecco is not free at St.Regis, unlike one free glass at SGS and unlimited free at Athenee or even Le Meridien. I did like the fresh specialty juices of St.Regis which were more changing than food, for example there was beetroot juice and watermelon juice one day, coconut water and carrot juice the other day.  

In terms of the environment for breakfast the views at St.Regis are great, but space is a bit cramped in some parts of the restaurant. One morning we sat near the windows in the middle section of the restaurant with one line of tables and walls on each side (which is not on the pictures).  When going to the buffet we had to squeeze between the occupied chairs and the wall.  If you add that to the traffic from staff, I can confirm I would not have appreciated having a chair closer to the buffet and having several people walk right above my head with plates of food.  Other parts of the restaurant were better, but regardless this is in contrast with the more vast restaurant at Athenee and the very private breakfast at Rossini for Platinum guests at SGS.  

Service

In terms of service, as good as SGS is, St.Regis is even better.  St.Regis stands out with the butler service and other attention to details.  For example, we did not notify the hotel in advance of a special occasion for our visit because we were laid back and did not intend to demand anything extra, but when chatting with staff at check-in we told them about our special occasion.  They went out of their way the next day to bring us a written note and a gift to our room – this was a very nice touch.  I also appreciated having 4 free pieces of laundry per day for a couple (so 8 pieces total in 2 days) which was very convenient during a long trip; this is not something we can get at many other hotels in the city and it’s a valuable service.  

Overall

All in all yes I can recommend St.Regis Bangkok particularly to travelers who highly value great service, and/or travelers who do not have status with any hotel chain.  If I compare to Park Hyatt, I believe St.Regis is better value all things considered. I have not been to the new Waldorf Astoria yet, but so far based on comments I read, I also think St.Regis is a solid choice and I am not in a hurry to book at Waldorf.  So in its hotel class, St.Regis is good, but where St.Regis might not be the best choice of all travelers is if you start comparing with other choices within Starwood/Marriott particularly since the hotel chain is so strong in Bangkok.  Part of my general attraction to other options within Marriott/Starwood is that it should be noted that for my own purposes I value a butler far less in Bangkok than in other parts of the world so one strong point of St.Regis is muted for me, which of course is different than other guests.  St.Regis is the most expensive of all Starwood/Marriott hotels, but in my situation I am not sure I get the best bang for the buck at this hotel.  It is probably easier to get suite upgrades at some other hotels in the chain than St.Regis if that is what you care about.  Breakfast is good but I think no better than #3 in my book, and even #4 if you count Grand Hyatt.  For happy hour you get a drink voucher per day per person, which is inferior to LM or SGS, and significantly inferior to hotels with a lounge such as Athenee or Marriott legacy hotels.  Unfortunately we were jet lagged and did not even use the vouchers.  When that happens in a hotel with a lounge, clearly you do not get a rain check.  Because vouchers are perhaps a bit different, I thought I would at least ask at check-out if we could use the vouchers during our next visit, but it was denied.  Oh well.  

Given the price of St.Regis then I can say it’s a solid hotel compared to luxury options outside of Marriott/Starwood, but if you are Marriott Platinum and if you are somewhat price sensitive, in my opinion I think the sweet spot remains with other hotels within Starwood if you are willing to compromise on service.  For people without status, as mentioned above St.Regis is a solid choice because the standard room is excellent and without status you won’t have free happy hour at any hotel so the lesser Platinum happy hour at St.Regis would be a non-issue.