WWOZ plays their daily live music calendar at the top of the odd numbered hours, all day every day. It's also on their website
http://www.wwoz.org
Frenchmen St is immediately downriver from the Quarter, actually the BMC (Balcony Music Club) is right on that corner of the Quarter proper. It's about 1.5 blocks from the BMC to the start of Frenchmen. Jon Gross and Tom Saunders play at The Spotted Cat quite a bit, Tom is as often on bass sax though. Matt Perrine plays with several groups, but find him with Tin Men or anything else with Washboard Chaz, especially. Aside from those 3 guys, and Bernie Attridge occasionally, most of the clubs use string bass exclusively. That was one thing I hadn't been told, or figured out ahead of time, when I tried moving there. The street bands use souzies, obviously, but not so much in the clubs. Other clubs are the Maison (aka 508 Frenchmen if it's still open), Snug Harbor (see if Ellis Marsalis is there on a Friday when you are...worth the money, but he sells out far in advance) has good stuff a lot of the time, and the food is good.
In the Quarter proper, Fritzel's on Bourbon, the Palm Court Cafe (FOOD), and one other (the name is evading me) are really about the only jazz/horn oriented places, and no tuba there usually. During the daytime, Royal St gets closed for a couple blocks and street bands take over--the Loose Marbles get a fair share of the time there. Street musicians on Bourbon have to quit at 8pm, but there are others going later in other parts of the FQ.
It's a great city, take time to ride the streetcar down St Charles, drive through the 9th Ward to see what the media doesn't report any more, and eat. Eat. Eat. and drink in moderation if you're able and legal. Go up to Treme' and see the neighborhood that inspired the tv series. You can't see the Mississippi Queen riverboat any more, it's been dismantled. But, go sit on the riverfront, and go to suburban Metarie, get a bag of shrimp, and sit on the Lakeside and eat 'em. A great way to relax and dig the scene away from the noise of the city.