Soi 57 wins on the rooftop bar. SGS has great breakfast venues and very convenient to shopping and transit. St. Regis is an overall stunning property, with the best pool, but rather sedate. Something else you may want to consider is ease of transport to BKK. I would cross off the Marquis on that basis. The first/last quarter mile on Soi 22 can be particularly brutal. Soi 57 probably wins there (assuming you are going by car).