Down through the decades, Conde Nast, the publisher of glossy, upmarket titles from Architectural Digest and GQ to Vogue and Vanity Fair, has generated enough buzz and chatter to fill a million gossip columns (which, truth be told, it has). Now, Madison Avenue is agog at the latest twist to the long-running saga at the US's most prestigious purveyor of magazines, which, after eschewing business as usual, seems ready to, gasp, embrace normality.

Last week, Steve Florio, the high-profile president and chief executive of Conde Nast, surprised agencies, advertisers, colleagues and competitors by revealing plans to step aside, effective 16 February, to become the vice-chairman of Advance Magazine Group, which oversees the fabled Newhouse family's holdings under the Fairchild, Golf Digest, Parade and Conde Nast banners.

Florio has become famous for his hard-charging mien and larger-than-life personality, as embodied by his natty pinstripe suits, regular table at the Four Seasons restaurant, large cigars and annual holiday season "Italian guys lunch" at which executives including Florio, his brother Tom, the publisher of Vogue, and Ron Galotti, the model for the Mr Big character on Sex and the City, would gather for afternoons of politically incorrect fun.

Florio's persona was in marked contrast to his boss, the low-key, almost reclusive, SI Newhouse Jr, known to his stable of talents such as Florio, Anna Wintour and Graydon Carter as Si.

Officially, the decision to leave was Florio's, prompted, he said, by desiring a lifestyle change after 25 years at Conde Nast, ten of them at the helm, and finishing 2003 with what he proudly called the company's best performance ever.

There was speculation that health issues were involved. Newhouse, known for arriving at Conde Nast headquarters before the dawn does, was described in The New York Times as "increasingly uncomfortable" with Florio's health-related absences amid 18-hour workdays. Florio, typically, dismissed those whispers with an earthy epithet.

Whatever the reason for his departure, there is no arguing that under Florio Conde Nast has flourished. Inheriting a company with 13 titles, he leaves with 17, soon to be 18, with the spring launch of Cargo, a men's version of the successful women's shopping title Lucky, introduced in 2000. There were other start-ups such as Teen Vogue, acquisitions such as Wired and the transfer of The New Yorker to Conde Nast. There were setbacks, including the closure of Mademoiselle, and Conde Nast was tarnished by a 1998 profile of Florio in Fortune declaring in his hands, "truth is a fungible commodity".

The belief that Florio's farewell marks the end of a big, colourful era and the start of more sedate days is being prompted by who his successor is: Charles Townsend, the chief operating officer of Conde Nast and Advance Magazine Group. Townsend has been the proverbial Mr Inside, tending to mundane matters such as circulation, technology and human resources, as Florio, the quintessential Mr Outside, led the ad sales and corporate marketing efforts. Now Townsend, more spiritually akin to Newhouse, will head the house Florio built up.

And what of Newhouse, age 76? "I seem to be functioning well enough," he told Advertising Age, "and I hope to continue." Maybe he should ask the boss. No, wait, he is the boss.