If you are looking for wade fishing you need to head down to Grand Isle area. If you are looking for a guide service Look up Capt. Jody Donewar out of Myrtle Grove Marina or Capt. Phil Robichaux out of Lafitte.
If you only have 7 hours think lafitte (only 45 min from downtown). Robichaux is the most popular guide but you may be able to call around and find someone cheaper for a half day trip. If you have cash to burn and a three people to split the cost check this seaplane website out. They fly you out, catch your limit and come home in less time than it takes for you to get down there. Plus a post katrina seaplane ride would be amazing. http://www.southernseaplane.com/index.php
Easy, go across the Slidell bridge (if its still there, rent a rowboat with a small outboard at the base of the bridge (if its still there). Fish the railroad pylons for big fat trout using soft plastics, or live shrimp. (if the bridge is still there). Catch a bunch, because, they are still there!