New Orleans really gets going from Oct (Halloween, plus that's when it finally starts cooling down) thru May (crawfish season, outdoor festivals, jazz fest, fq fest etc.)  Mardi Gras is great for tourists but tough for hotels because everything at least doubles in price.  My favorite time in Nola is April/May because the cities still popping but your clear of the madness of Mardi Gras.  French Quarter is always good for hotel deals but can be problematic for parking.  The cbd is adjacent to the French Quarter and has a ton of new hotels.  Hope that helps!