Did you stay in club rooms at Sukhothai, or in the main wing? My previous review was a club suite, therefore the same as the review of
lost_in_translation . For my subsequent stay at Sukhothai I booked in the main wing simply because I was burning Hyatt cat 1-4 free nights. The rooms in the main wing are night and day with the club rooms - very old, unrenovated, very low ceilings in the bathroom, struggling air conditioning, etc.
In many hotels, booking club room or regular room comes down to whether you want to pay for lounge access. Here it's not the case at all; the rooms in the club wing feel like it's a completely different hotel so even if you want to skip the lounge it's worth the extra. I will never go back to Sukhothai for the rooms in the main wing - I would rather burn my Hyatt free nights elsewhere. And if you are paying cash, then those entry level rooms in the main wing are badly priced relative to the competition for the state of the rooms, Park Hyatt included.
And regarding service, I ran into the Sukhothai dogmatic attitude that frustrated me before, and also noted in lost_in_t"s review. One example: the gym opens at 6am, I asked them to open the door for me at 5am and they said no. First off most luxury hotels have 24/7 gym and if not, even a lowly Sheraton will normally have staff available to unlock the door. Sukhothai is maddening. At PH sometimes the service at breakfast is not overly impressive but some other aspects are quite good, for example the concierge personally moved one of my bags in storage (after I left PH) from PH to Sukhothai which was very nice and avoided me same hassle. So all in all, in my experience Sukhothai is NOT far better than PH in service. Both are ok, some strong points and some room for improvement as well. Service is better at Sukhothai if having access to club lounge staff.
My recommendation is to only consider club rooms and club suites at Sukhothai, the rest falls short of luxury level, both the service or the quality of the rooms.