Nice in a Week is not the kind of book on this list — what's here are novels and memoirs that open up what Nice feels like beyond the seafront.
Graham Greene, J'Accuse: The Dark Side of Nice (1982). Greene lived in Antibes and became obsessed with local corruption, eventually publishing this pamphlet accusing the Nice establishment of protecting criminals. It caused a scandal, was partly retracted, and remains a portrait of the French Riviera's less glamorous underbelly.
F. Scott Fitzgerald, Tender Is the Night (1934). Set largely on the Cap d'Antibes near Nice, this novel about American expatriates disintegrating under Riviera sunshine captures something true about the seductive, corrupting quality of this coastline. The Nice of the 1920s functions as backdrop and accomplice.
Tobias Jones, The Dark Heart of Italy (2003). Not specifically about Nice but essential reading before any visit to the border region — Jones spent a year in Parma making sense of Berlusconi's Italy, and his observations about the Italian character that suffuses Vieux Nice are sharp and useful.
Martin Page, How I Became Stupid (2004, trans. from French). A comedy about a philosophy student in Nice who decides intelligence makes him miserable and attempts to become stupid — it is funny and light but captures the particular self-conscious culture of a city that thinks of itself as more serious than the Riviera reputation suggests.