Bangsaphan Bars
Bangsaphan does not really have any nightlife scene as such, at least nothing compared to that in Hua Hin, Samui or Phuket, it is a quiet local town that is just starting to develop. Many feel that this is part of its charm and it should remain this way. The town is generally closed up by 10pm so if you want to party stay on the train!
There are a couple of rock music bars in town including one called the Blue Moon (Ban Mai) which also has a live band and can get very busy. Tung Pub is also a rock venue just a kilometer from town on the road to Suan Luang, it can get very busy with young Thais at the weekends and there are often fights. A new venue at the Check In hotel in town also offers live music and a range of expensive import beers.
Beach Bars
For those that would like to relax during the afternoon and early evening there are a couple of small, friendly beach bars in Suan Luang where you can sit and take in the views.
Montri’s Coco Bar is a rustic little place that has become somewhat of a Bangsaphan legend, however times are slowly changing. It is a good spot for meeting the local expats or listening to some rock and roll during the afternoon.
Country Road Bar & Restaurant was a new addition to Bangsaphan in 2013, around 200 meters from the beach. It offers good food, a huge selection of music, and a cowboy/biker theme, also a good place to meet the expats for some local knowledge. 
Why Not Bar is a little further down the beach, it is also a nice place to relax with a beer and catch up on sporting events. Why Not stays open later at weekends when there is often live music.
Blue Bar is a little further up the hill and has spacious garden seating and a pool table, it is often open a little later than the others and is popular with the locals.
Bew Beam up on the main road has a bar offering cold beers, cocktails and liquors. @ My Home Resort now has a little bar and a pool table and the newly opened Coffee Black/Maprao Kitchen serves cold beer.
Karaoke Bars
There are no shortage of karaoke bars around Bangsaphan, they mainly cater to Thais so you will struggle unless you can speak some of the language. VIP rooms and massage services are on offer along with the usual extras however again these are generally only available to the locals! There are many of these type of venue round where the port is at the far end of Mae Rampheung bay.
Most of the hotels and resorts have their own bars but they generally tend to be very low key and somewhat over priced.