View from the Sky Bar at Zepplin located at the 46th floor of Le Luk condominium B Tower at W-District Sukhumvit Soi 69. See location tag. Open from 18:00 to 2:00. Besides a great view of almost 360 degrees they serve a great cocktail collection and a small Thai & Western menu. Prices are not cheap ... actually expensive. But the service is great & the cocktails fantastic.
Update 2018 : I think it is nowadays called Cielo Sky Bar & Restaurant. Open from 17:00 to 24:00.