My favorite dish at my favorite Thai restaurant is a type of curry. I don't know what its called, but it is a bit unusual in that the curry sauce is made using dry ground spices as opposed to the wet curry paste used to make yellow, green, red, penang or musamun curries. I just tell them I want "the other curry"! They know me well enough and know exactly what I am looking for!
Drunken noodles with chicken. The hint of mint, the heat of chilis. The crunch of broccoli and the succulent noodles. Just yummy. I have to try your Sea Bass with lemon grass, though. That sounds awesome. I'm always looking for good (and easy) fish recipes. There are only so many times you can bake a piece of salmon.
Having worked in Thailand as a chef for five years there are so many favorites but I would have to say either Larb Gai (spicy minced chicken salad) or Yam Nua (spicy sliced beef salad) or Tod Man Pla (fried fish cakes with spicy cucunber salad).
I asked friends in your city about Thai food restaurants and all say only in Hong Kong. I have only eaten local Guangdong cuisine in Shenzhen. Sorry not be able to give a suggestion. You might ask at Western style hotels if they have a Thai restaurant as that would be the best place to find this delightful cuisine.