You might not know but adjacent to On Nut BTS station ( skytrain ) there are 2 great places. On one side is Tesco Lotus and on the other side is On Nut Market.
If you want a great place to eat cheap food and drink well, On Nut Market is the place to go. The market has numerous food stalls selling Thai and Western food, many stalls selling clothes, and three covered but outside bars. Two of which have live bands regularly. The bars have a nice relaxed atmosphere, there is no hassle and no pressure to buy drinks. The local Thai patrons are friendly and a nice evening can be had in their company.
I recommend it to Thais and Farang together, and also recommend the pizzas which are available near the bar at the back. Likewise, if you like cocktails at very good prices then the Cocktail Bar is for you. It is in the center of the market on the right hand side as you look from the BTS station.