The surreal madness of Saturday night in the French Quarter was only a few steps away, but inside the Chateau Sonesta Hotel, where budding jazz diva Kim Prevost and Guitarist Bill Solley hold court most weekends, the clientele basked in a much more soothing glow.

The song was “Days of Wine & Roses,” Solley’s rich chords and nimble fretwork complementing Prevost’s smoky, sou...