There's so many choises. Most of them are restaurants that also have live music and it's all good but, if you're looking for the real deal, go to La Poussiere dance hall in Breaux Bridge on Sat. night and dance to the music of Walter Mouton And The Scott Playboys. It still is what it used to be 30 years ago.
This may not be as easy for you as it is for me (I live in Maryland); but if you can, listen to Pete Bergeron's radio show on KRVS.org on the computer.
He is on Monday through Friday from 5:00 to 7:00 (6 to 8 for me). Every day, he gives places and dates for restaurants, jam sessions, dances, etc. Of course I don't understand French too well and I often can't tell when the events are happening, but I always know where. He often mentions places in Crowley, Rayne, and Jennings.
One other place that I have found to be a lot of fun on Thursday nights is a jam session at Nick's in Eunice. Every time we have been there, it has been a lot of fun. Larry Miller ususally is there. Also, Kyle Huval, the son of the guy who runs the jam, is ususallyu there. He is one of the best young accordion players that I have heard.
If it's the weekend, you've got plenty of choices, for sure. A nice time is to go to Henderson, east of Lafayette, and eat a stellar meal at Pat's... then walk next door to the new, Atchafalya Club. There's usually a great band playing (Geno, Travis Matte, Kevin Naquin, etc.) It's nice, comfortable and huge with plenty of room to work off all that rice and gravy. Then, when the dance is over, you can get the remainder of that 40 oz. dacquiri you got at the Paradise drive-thru out of your car, climb up the levee, and howl at the moon! C'est fun!