Wow, where to begin... LOVE the city! I'm jealous.
For food, don't miss Mother's or the Gumbo Shop. I think you'll be there during crawfish season, so shut up and suck it!!

(You'll figure out what that means) Cafe Du Monde for beignets (kinda like donuts) and cafe au lait... ohhh yeah. Also, the Central Grocery is where they have the SUPER delicious muffaletta sandwiches. Hard to describe, you just have to go try one.
Bourbon street is fun in the evenings, great place to people watch and just wander up and down with a nice cold beverage and take it all in. Safety in numbers, don't wander too far north from Bourbon.
If you don't mind walking, check out the walking tours - the haunted tour was fun, they do it in the evening. I also enjoyed the evening riverboat dinner cruise on the Natchez. Music and dinner. There is a casino (Harrah's) if that's your thing. There's also a pretty decent flea market if you want to bring back some souvenirs.
Have fun!