I just went in February for Mardi Gras and got some GREAT advice from this board! It was an awesome trip, and I loved being in a random city and doing all the touristy stuff. I actually want to go back because I didn't get to do everything I wanted to do because Mardi Gras activities took up a lot of our time (But, if you ever get a chance to go, I would definitely recommend Mardi Gras!)
-Cafe du Monde, as others have posted. Don't worry, you won't miss it! It is right across the street from St. Louis Cathedral in the French Quarter
-Go to an Absinthe Bar. I've had Absinthe before, but it is a rare treat, and there are a few absinthe bars in the FQ who will serve it properly. The only other time I have had Absinthe served properly was in actual France, so it was nice to have it in the little French Quarter of the USA.
-Muffuletta from Central Grocery-huge meaty olivey cheesy sandwich!!!
-Pat O'Brien's-I loved the atmosphere in this place! They have dueling pianists (think Jellyrolls) and it's a really awesome place with a nice courtyard. They have hurricanes, but I got a Mint Julep and it was SO good, really strong, and only like $6!
-Walk around the French Quarter and take it all in! It's a lovely place. Walk down Bourbon Street and people watch.
-Take a tour of the cemeteries. Really cool!
-WWII Museum was AWESOME!
-Take the streetcar up to the Garden District and look at all the beautiful homes. Seriously gorgeous place!
-Somebody here on disboards reccomended the restaurant Jacques-Imos, and that was actually probably the single best tip I got for my trip! One of the best restaurants I have ever been to, and, being a Northerner, I loved trying all the food that is unique to that area! I tried the Alligator Cheesecake and the Blackened Redfish, and both were phenomenal!
We didn't go because it was closed for the holiday weekend, but I heard Preservation Hall is a don't miss if it is open when you go!
If your DH likes cigars, there is a shop on Decatur Steet called Cigar Factory of New Orleans, and my grandfather spent about $300 on cigars there because he REALLY liked them-so worth checking out if you're into that.
Also, you can walk around the streets with open containers of alcohol, and I definitely found the novelty of being able to do that a fun part of my trip, lol!
Also, you mentioned that you want to try New Orleans food: Some things I tried while I was there that we don't see commonly or ever in MA were alligator, blackened redfish, po boys, gumbo, jambalaya, and crawfish