Hard to say how many days would be sufficient, I live down about 1.5 hour down the road and visit often and still havent done it all.
D day museum
Aquarium
Zoo.. too hot for me in the summer though
Cemetery tours
Long Vue house
River Road plantation tours
Swamp tours
French Quarter Bourbon street Pat O's for sing along fun
Adult clubs on Bourbon if that is your cup of tea
The Shops at Canal Place for high end shopping
Royal street for Antique shopping
Jackson Square for art and fortune telling
French Market for yummy veggies & flea market junk
Magazine Street for fun local bars and boutiques
Mardi Gras Museum.
THe Cabildo at Jackson Square
Horse buggy rides around French Quarter
This is just the the things I can think of off the top of my head . I didnt include all the places to hear amazing Jazz music, Ill have to look those specific places up to give you names.
It is very hot in the summer, I could honestly spend a week eating my way around Nola .. that is just eating LOL. I never have enough time to hit all the good places.
Gambling would be the LAST thing I would spend my time in NOLA doing lol.
Come visit us on the NOLA thread for more specifics.
We are foodies so we can tell you all the yummy places to hit besides Cafe Du Monde : ).
http://www.disboards.com/showthread.php?t=2430241&page=62