On the the thread no more smiles, mention was made of gay bars in Soi Nana. In the mid to late 90's the fore runner to Utopia was located there and had a gay shop with accomodation upstairs. I think the owners name was John and Soi nana was walking distance.
I found the cut and paste below on google. It would be interesting to hear more about this area as the only area outside Silom usually discussed is Saphan Kwai
Gay-friendly Neighborhoods in Bangkok
While gay bars can be found almost everywhere throughout the city, there are actually three hot spots for gay entertainment in Bangkok.
Silom Road, next to the Sala Daeng BTS Station and the Rama IX intersection, is probably the best-known gay area in the city. SoiтАЩs (sub-streets) 2 and 4 are home to an extensive choice of bars and discos while hotels can be found on the parallel Surawongse Road.
The second gay-friendly area in Bangkok is Sukhumvit Road, mostly between soi Nana and soi Asok. However, most establishments in that area specialize in adult entertainment.
Read on
Finally, the area around the Ramkhaemheng University has a few bars and discos, mostly frequented by a younger local crowd.
Gay Bars and Discos in Bangkok
Note: For ethical reasons, bars which provide adult entertainment are not listed here.