I have been staying at sukhhumvit Crown Hotel for over 30 years. I lived there for 3 months in 1982. My wife is Thai and we stay there for about 3 weeks, every second/third year. It is not a custom for Chinese to smile when giving service, but on the whole the staff are very helpful and will help with any problem you have, if they can.
The service is excellent and rooms are cleaned daily and food can be delivered to room and a buffet breakfast each morning to 10.30am. Definitely value for money, but not the Ritz