Don't know what to tell you about Herbsaint, never eaten there.
Cochon would be the right atmosphere. We were thinking of going there too, but decided - why go all the way to NO to eat basically the same meal you can get here at a place like Publican or Bristol? NO has such a distinctive cuisine that's somehow managed to avoid getting homogenized, for the limited time I'm there I want to get as much of it as I can. I'll save the burgers, Thai, Italian, porkmeisters, etc for when I get home. A place like Galatoire's, you ain't gonna find that nowhere else on this planet.
Any of these places are within a 10 minute walk from the Sheraton, that location's right in the middle of everything.