I've stayed at the IC many times, HI Chateau Le Moyne several times, an the CP on Canal once or twice. If they are looking for more of a "French Quarter" experience, I'd recommend HI Chateau Le Moyne. It's historic with that French Quarter feel, in a quiet locstion with a beautiful courtyard.
As a Royal Ambassador, I do love the Intercontinental. It's a great hotel just on the other side of Canal, closer to the casino with recently renovated rooms. Not sure if I'd stay there if I wasn't RA, though.
The Crowne Plaza was fine, too but nothing spectacular.