(Very Long report from an evaccuee)
I've been reading, but I haven't had time to write until now. I evacc'd N.O. on sunday 8/31 at noon to Jackson MS and now I'm in Baton Rouge, LA (80 mi from N.O.). I have my parents (70+) with me at my uncle's house. My GF went to Nashville to stay with her daughter.
Most of the comments here have been in the X ring, but you also have to accept the fact that if you're getting your news from the nat'l/world media, you really don't have much perspective.
For perspective, here are some key points I haven't heard from the media in any meaningful detail.
Overall: The New Orleans metro area consists of four parishes (counties); Orleans (which is the city proper), Jefferson, St Bernard, & St Tammany.
Orleans Ph is probably half a million and 80% black. Most of what you have seen on the news has come out of Orleans Ph.
1) All four of these parishes have been seriously damaged by Katrina. It has been esimated that every house in predominantly white St Bernard Ph has been damaged by either wind and/or water. The Emergency Director for St Bernard has said that so far (as of 9/4), FEMA's assistance has been "zero".
I have been up here, in gasoline lines and whatnot, with all kindsof people, rich, poor, black, white, you name it.
2) Beginning Friday night, gov't officials all over the area begged us to leave, eventually raising the alert level on Sunday moning to "mandatory evacuation". This does not mean that they come to every house and put you in a truck against your will; that's impossible.
What it means is that they tell you, and they did tell us, time and F 'ing time again, that you are on your own if you stay. No police calls, no fire calls, no food, no water service, no electricity. Probably no gas.
They F-'ing begged us to leave. On TV, radio, even a special messge to by read by all religious leaders to their congragtions on Sunday. They asked church congregations to pair up and get ther elderly out.
I've lived there almost my whole life, and this is my first evac. They convinced me. Along with 80% of the population. But a lot of people here have a 'manjana" type attitude, mixed in with stubborness.
All the weather people agreed this would be extremely bad and would not in all likelihood change it's course away from us. (Sometimes the weather people disagree). This time it was unanimous.
It takes about a day to get a house ready: garbage cans and furniture inside, windows boarded up, food and batteries if you need that, pack gun(s) and ammo, pack clothes and valuables/important papers, valuable stuff you can't take up high on table tops, gas up the car.
This is one of the problems with using say, school buses, to get people out. You can't "draft" school bus drivers, plus the competent ones are getting their own stuff ready and and then leaving with their families. The shitbags are not going to show up anyway.
3) They advised time and F 'ing time again, "Do NOT plan on using the Superdome for a shelter! It is not equipped as a shelter. You will be miserable if you go there. It is shelter of last resort. You have to bring your own food water and bedding. There are real/better shelters waiting for you inland. Do NOT plan in using the Superdome as shelter!"
People drove there in their cars Sunday night. (Storm eye arrived Monday am)
4) Wind driven water from the lake "topped" a levee in middle to upper class black neighborhood. This was damaging, but temporary.
There were two levee breaks in drainage canals. These accurred because the volume of water being pumped out caused erosion ("scouring") in the bottom of the levee, causing them to crumble.
First in one bordering the Lower Ninth Ward, a poor black neighborhood (where most of the heli rescues were videotaped) , then later on, in one bordering "Lakeview", an affluent white neighborhood. Most people who had remained behind in Lakeview still had time to see how bad the storm was and evac after it passed, but before that levee broke.
These two broken levees have caused a vast amount of the problem you have seen on TV. But there is just no way to precit where a levee will brak.
5) The NOPD (Orleans Ph only, the other parishes have Sheriff/Deputy LE Orgs) is undermanned by about 500 officers (desired is 1,800, actual is about 1,250) to begin with. About 400 are currently MIA/AWOL. Two are confirmed as suicides.
They exhausted their emergency provisions and had to "loot" more to survive. Once their radio batteries ran down and couldn't be recharged, they were without commo. In some cases, their rank was MIA. Not impossible to overcome, but damned inefficient.
I heard one first hand, face to face account of an attack and firefight at the 1st District (precinct) Station.
6) Gov't officials do run planning exercises and scenarios here, believe me. The problems you're seeing have occurred, in part, because much of the infrastructure to be used in the plans has been destroyed. Bad Luck of the draw, "perfect storm' type outcomes. So, they're operating on the second and third tier contingency plans.
7) Of the four main highways serving NO, two are out of action (I-10 East twinspan bridges of town (gone) and the Causeway Bridge (requires inspection for safety). I-10 West survived, and Hwy 90 was apparently under some water until a day or so had gone by.

Important for LEOs-The hospital attacks you have heard about were apparently triggered when junkies/addicts were without their usual "connections" and therefore attacked hospitals for any drugs to take the edge off. Remember this for contingencies if something similar happens in your AO.
All for now; I'm tired. You're probably tired of reading this.