Did this last year. Went through the French Quarter, 9th Ward that was devastated by Katrina, Garden District, etc.
You can also do a ghost tour through the French Quarter, which was interesting from the stand point of the actual history of the area, even if the alleged paranormal stuff was a little strange.
There also a number of plantations you can tour. We visited one in Destrahan, which is only about 30 minutes west of New Orleans.