On any given night, a festive crowd will find its way to the Mississippi River and aboard the Steamboat Natchez, where the DUKES of Dixieland play an early-evening cruise, seven nights a week. Maybe they’ve come to witness a living piece of New Orleans music history, or maybe they just want to tell their grandkids they heard “When the Saints Go Marching In” on a riverboat. In any case, the band will d...