This is one of my favorite hotels in Bangkok (although there are many great choices -- Marriott Soi 57's sky bar Octave was amazing, and the pool at SGS is excellent, and the river views at the Peninsula). I stayed 3 times in August/September. My first one-night stay was upgraded to a suite; second 2 or 3-night stay was upgraded to a round-bed room; last stay was a suite.
Every time, the doormen/bellmen, front desk, restaurant staff, etc. were excellent. The manager at the Latest Recipe and the bartenders at Bamboo Chic were truly exceptional -- they knew my name and preferences after the first day, and the service was as good as I've had anywhere. Breakfast had a huge array of Thai/Indian food, Western food, and Japanese food, as well as fresh fruit, baked goods, etc., and was as good as the (excellent) food at StR buffet, Rossini at SGS, and Marriott soi 57.
Drinks at Bamboo include a selection of 3 appetizers, charcuterie, and shrimp chips. I discovered I actually prefer the mocktails to cocktails (at least a 1:1 ratio), but everything was great. It's definitely possible to just eat breakfast in the morning and appetizers in the evening, but I also went out to some nearby Japanese restaurants a few times.
The "Le Meridien Experience coordinator" Loic also introduced himself during one of my check-ins, and was super friendly and informative. Apparently the hotel might be renovating some things next year, and while I initially couldn't see what could use it, I guess there are some furnishings/etc. which are slightly worn in some of the rooms (the downside of the Meridien style, which is a style I really like, is that wear shows up more than with more "traditional" design). There do seem to be better rooms/suites on the top floors (e.g. 1724) which have things like the Japanese toilets, compared to suites on lower floors, and maybe the wear is more apparent in the lower tier rooms (which I never see). It's already a great hotel; if they remodel anything, I can only expect it will get better.
The bathrooms are probably my favorite anywhere. Great rainfall showers, and in the suites, two separate rainfall/hand shower areas in a long shower room. Plus, an "American sized" deep bathtub. Beds and decor were great -- the desk, especially in the suites, has a decent working area with a comfortable chair, there's a Lavazza coffee machine, and the TVs are huge.
I didn't use the daytime soda/drinks area of the restaurant, although it is nice to have available.
Overall, I'd always stay here when it's <4000 THB, and even at 4500 it's not a bad deal. There were a few times when the price was comparable to SGS, and I'd always do SGS+LM on a trip vs. just one of them, and maybe the SGS is worth 300-500 more per night due to location and pool, but it's a hard decision.