Richard & daughter & all:

The schedule of who's playing where in New Orleans varies on a nightly basis, of course, but here's a general guide to where "real" music can be found:

Little or nothing within the boundaries of the French Quarter (as you seem to have learned), EXCEPT:

Preservation Hall, which most people know about, on St Peter St just off Bourbon. Early start (7pm?), no liquor license (BYO).

The Palm Court Cafe is the other spot for authentic traditional jazz. Live music in a fairly classy restaurant setting. You can sit at the bar, but for the full experience, get a table and have dinner and sit through two sets. (Or show up later and sit down for coffee and dessert.)

Irwin Mayfield's new club in the 100 block of Bourbon, attached to one of the newer hotels.

Then there's Frenchmmen Street, just outside the Quarter (i.e., just "beyond," or downtown, from the corner of Decatur and Esplanade). One well-established club on the strip, Snug Harbor, has long been the city's #1 venue for contemporary jazz. In more recent years, a whole bunch of music venues have sprung up all around the Snug, a dozen or more in a three-block stretch. You can listen at the door to tell whether the current act at any given place is something you'd like to hear. This is an absolutely "happenin'" scene ~ some stuff might be a bit too newfangled for the older folks among you, but most of what you'll hear is pretty much folk/blues or jugband or trad-jazz based. Few of the clubs are large enough for really loud rock music, and what "rock" you'll find will usually be funky and/or soulful, not headbanger or techno crap.

Outside the FQ and Frenchmen, check the lsitings for what's on at:
Tipitina's (legendary, but no lonter open every night)
Maple Leaf Bar
Rock n Bowl (relocated since Katrina! Check you map...)

Extra-special on Thursdays only: Kermit Ruffins at Vaughn's Lounge, now starting at 8pm with a $10 cover. (Used to start very late and cost only $5.) If you spend only one evening in the city listening to music, this is IT, absolutely not to be missed.

And then, for low-key acoustic mostly-folkish music of wildly varying quality, there's the Neutral Ground Coffeehouse, far off the beaten track at 5110 Danneel St., way uptown near St. Charles & Jefferson Ave. Three or four different acts per evening Mon-Sat starting at 7 or 8, one hour each, and open mike every Sunday. With more than 100 acts per month, it's hard to predict who and what you might see and hear. Anyone from touring professionals with no better-paying opportunity that night, to tone-deaf angst-ridden college-kid "songwriters." I'll be appearing 8pm Tuesday March 23, and usually on the 4th or 3d Tuesday of every month at that same hour.

I'm sure I left out something, but that's a start...