St. Regis Chengdu is my favorite St. Regis. The service was beyond amazing, they truly went above & beyond.
A bit of backstory: I had my phone stolen in Shanghai right before checkin in. Arriving in Chengdu, I asked for help figuring out where to buy a temporary phone. The butler staff accompanied me to stores to go check out options (the translation help was an absolute life-saver) and help me purchase one and sign up for a local plan. Since I couldn't sign up not having a local ID, one of the butlers used his personal ID to sign up for the plan (trusting me, since he's on the hook for any overages). Also, the head butler offered to lend me his personal phone for the duration of my stay, since it was much nicer than the temporary Huawei I bought.
This was all completely unprompted.
The hotel was truly excellent in many other ways, too.