Sukhumvit is, perhaps, the longest avenue in Bangkok and the one with the most hotels and tourist jaunts. With the Skytrain running overhead, it makes it into a convenient location to stay with easy access to the city’s public transport system. The side streets, or sois, in Thai, running like a fish spine all along Sukhumvit are numbered. The numbers increase eastwards and are different on the left and right sides of Sukhumvit. Sometimes on the right you will have Soi 34 and on the left it is still Soi 20.
Far from the throngs of budget tourists that cram the area, you will find Thong Lo, or Soi 55. There is a Skytrain stop with the same name and you can start your explorations from it. Walk northwards along Thong Lo and you will be surprised by the amount of bars and restaurants lining up the road.
The best time of the day to explore Thong Lo is from sunset onwards, for happy-hour, dinner and maybe and extended night out at a club.
Running parallel to Thong Lo and also full of interesting options is Ekkamai, or Soi 63. Just head to either 55 or 63 and you will not be short of options.