Stayed at both the FS and Sukhothai in the last two weeks and here is my comparison:

1) FS - the hotel is under renovation though I don't hear any noise when i am there. The hotel has been around for a long time and didn't notice any changes to the room since at least 5 years ago. Rooms are a bit tired though still nice. Service is excellent as usual.

2) Sukhothai - an utter absolute nightmare. I like hotels but am usually not too fussy. But my experience here was so bad that I vow never to return to this hotel. My room was far from the lobby. And when I walk there, I get to see all the various construction sites around the hotel. It almost felt as if I am passing through the service area of the hotel. Room condition was OK. Nice large bathroom. After dinner, when I returned to the hotel, the key to my room didn't work. Tracked down someone to open the door for me so that I wouldn't have to trek all the way back to the lobby. He opened my door and I asked him to switch the key for me. He then asked if he can do it tomorrow morning. What kind of service is this? At a 5* star, the staff doesn't want to replace a malfunctioning key because it is 10 pm? I asked him to give me a new one, he left the room and never came back. At night, I could hear the noise coming through from the two neighboring rooms. Not to mention everytime someone turns on or off their faucet. Didn't fall asleep till really late because of all the noise. As i was sound asleep, the alarm went off. AND I DIDN"T EVEN SET THE DARN ALARM! I guess the previous guest did and I would have thought any 5* hotel would turn off the alarm as a new guest moves in. Thought about going to the pool and it is even farther away than the lobby. As a matter of fact, it is in a separate part of the hotel. By this time, I have had it with this hotel and why bother to return when there are so many other nice ones around? Even right next to the Sukhothai, there is the Banyan Tree and the new Metropolitan. The FS, Grand Hyatt and Conrad are all close by as well and I would take anyone of those over the Sukhothai.