Thia Food
Over the years I have found there is really very little radiance in the quality and flavours of Thai food served by the roadside or in the big swish restaurants so unless you want Air conditioning ,table cloths , flunkys and mood music settle for somewhere on the street or with an open front with fans.
Another alternative is the food centres in shopping complexes and offices. One central paying point and use 2 or 3 different vendors.
Falang Food
Some of the "falang owned bars can be excellent value but you will find more of a differance in the styles of cooking between the "pub grub" and the high end haute cuisine restaurants and hotels..
and if you want fish speciality you could try the Fish market and restaurant on Sukumwit Soi 24