If you are after ladyboys, go on Grindr in Pattaya. I remember there were more ladyboys than boys. In Bangkok you may have to go to the straight areas (Soi Cowboy/Nana Plaza) as I think there are ladyboy bars there, but I'm not too familiar with that scene. Although in Silom, the bar that is next to Screwboys (Pink Panther maybe?), as I was walking past I had one girl approach me but I said 'I like dick' to which she replied 'I have dick' to which I really had no comeback! Otherwise, the usual boy bars are all mentioned here in this forum a lot if you peruse a little.