Well, being from N.O. originally and learning to boat while I lived there, I can officially say that you are fucked. I feel for you. As for boating, the closest real boating is alabama. Little river canyon is a beautiful canyon, and it would be easy to hook up with boaters on boatertalk if you are heading up there. The only problem is that it is rain dependent so you can't bank on it and you have to haul ass up there when it rains. The drive up to LRC is about 6hrs one way. As for reliable, tennessee and the ocoee are really the best bet. If you get skunked on rain, you can go playboating. If you get rain there are lots of good river runs and creeks. There are always shitloads of boaters up there and it would be easy to hook up with folks up there. The Ocoee is 9 hr drive from N.O. and maybe a little less if you speed your ass off. My game plan when I lived in N.O. was to drive all day friday to the Ocoee, and camp out friday night. Paddle like a bat out of hell all day sat. Get in an early run sun, head home at about 1pm and get some sunday night.
From what I hear, arkansas has some good stuff too, but its not a whole lot closer than the ocoee, and it is rain dependent with a lower concentration of boaters. Unless you have some arkansas contacts dialed I would just go to TN.
As for boating around new orleans, the mississippi sounds like crap. I'd be scared to get out into the river with all the big ass boats etc. This might make you laugh, but if a cold front comes through (Jan-Mar time frame usually), and the wind is N to NW at 20+ mph, the lake gets waves that you can surf. Pretty nice 3-4ft waves. I had some fun days surfing the lake waves. The problem is that it takes a monster front to generate that wind power, and its a rare thing. March is the best bet. I found a wind gauge on the wwl weather website and used to check it all the time. Pretty pathetic. The spot to go is behind the UNO technology park on lake pontchartrain. The lake would also be my first choice for flatwater paddling if you want to practice strokes and rolls etc. Watch out for big rains though, the e. coli jumps up right after a big rain.
I never checked it out, but there is supposedly some surfing to be had in the gulf of mexico about 2 hrs southwest of new orleans near morgan city or something like that. Never did it, but it sounded like shit as its an offshore shipping port.
I did talk to a few guys on boatertalk who would do some surfing at dauphin island in alabama. on the gulf coast. Its 2.5 hrs away and if the wave conditions are right, you can get some surf there. Never checked that out either.
So, as far as boating goes, its bayous, lakes and other forms of unexciting flatwater around new orleans. There is the class I+ okatoma creek in MS which is about 2.5 hours away that actually has "whitewater". I use the whitewater term loosely as there are a few very small ledge drops and the run is mainly a hick tuber and canoe run. If you like hick canoe carnage, then this might be an entertaining place to check out.
I think the best thing to do is plan on driving your ass off to TN, and plan some long weekends to colorado next season. I checked on plane tickets to chattanooga from new orleans, and since there were no direct flights usually it would end up taking as long to dick around at airports, rent cars etc, as it would to just get in the car and drive.
As for boating stores in N.O., Massey's in Metairie suburb was an outdoor gear shop that had some boating stuff (not sure if the are back after the storm) had some guys that kayaked and would go up to TN, NC. Those guys probably would have info on who might be boating in the area, as well as ideas for where to go. You might be able to hook up with them. As for meeting other boaters, it is slim pickings down there. I'd be suprised if you found any other boaters. There might be a few.
Texas really has absolutely nothing that is close enough to even consider.
Best of luck! Time to take up the best sport in New Orleans... Drinking.
I should also mention that North Carolina and Asheville are also possibilities, but they are just that much further from New Orleans and make for a long trip. The chatooga is also nice (GA/NC).