Actually, there are four (4) Tawan Daeng's in the BKK area. There is the Issan one you mentioned, there is another, very close by on the other side of the street (Music sometimes phua cheewit, sometimes more "wailoon" type covers). There is also the two German ones, one on Rama III, which has been there for years and provides good entertainment, good food, and great beer (IMHO the best beer in LOS, but I don't tend to like Thai beer). The other Tawan Daeng (German)is relatively new (about 2 years old) and out by Ram Intra, off the tollway, just before you get to Ram Intra Road -- so it is out in suburbs. It is set up like the one on Rama III, is about the same size or larger and has the same menu, the same style entertainment, and home-brewed beer. The one main difference is that it is licensed as as a restaurant, not a bar, which means, for those of you that have kids or teenagers, they can stay in the place until it closes, and not leave by 10 PM. This probably doesn't appeal to you mongers, but it important if you or your GF have teenagers and want to show them some fun. But then again, as mongers you might have a BG under 21 and she can get into this place and stay and enjoy the show.
Anyway, 4 Tawan Daengs, each with a little different premise, different music, different crowd. All fun and give you some variety. Your Thai wife, GF, BG, freelancer will all love these places and most likely you will too. I only wish that all four had the home-brewed beer, as only the 2 "German" Tawan Daengs offer the home-brew. Sometimes they have big name bands playing there, last year I saw Carabao at Ram Intra, cover charge 50 baht (yes fifty), but tough to get in, a queue of about 3,000 people outside. Jintara has played at the Issan Tawan Daeng.
Many of the working girls go to these places for their birthday party. An example, a good friend of a friend of mine used to work at the Star of Light (SOL) BJ bar, for her birthday she went and BF'd all her old cohorts there and even the new ladies, the owner/mamasan closed the bar and they were off to Tawan Daeng to party all night.