Indeed, the selection of books can be a more freighted process when publishing professionals are present. Louise Grunwald, the widow of the former diplomat and Time Inc. editor in chief Henry Grunwald, says the reading picks of her group’s leader, the novelist John Burnham Schwartz, sometimes prevail over other members’ suggestions. “It seems like a democratic process, but it really isn’t,” Grunwald said. “In the end, I find, it’s by fiat. But disguised as democratic.”

“You ask yourself, Should I fake it, or should I just admit I didn’t finish the book?”

Conversely, Coben finds that the novelists in his group are egalitarian: “Sure, there are elder statesmen and younger bucks. But no one dominates the conversation.” However, the presence of literary luminaries in the room can make a member’s unpreparedness especially piquant. “You ask yourself, Should I fake it, or should I just admit I didn’t finish the book? All members have done that at one point.”

Does Grunwald feel that being among the last left of New York’s acknowledged great hostesses puts a burden on her or on other members when it’s their turn to host? “I see what you mean,” she said. “But no. Everyone does his own thing. And sometimes people even have fun with it. If we’re reading an Egyptian novel, we’ll have hummus.”

What about Martel and his interior designers: Are kale leaves being massaged and couches Scotch-Guarded as we speak? “Yes, but convention steers toward studied casualness,” Martel said. Nevertheless, he added, “Sometimes the table is set for a night of taste and restraint, and then the rosé happens.”

For some hosts, the pressure to make the rosé happen is more plangent. The public policy-themed club attended by Sadik-Khan is always hosted by the group’s co-founder Gary Ginsberg, the senior vice president and head of communications at SoftBank. The group, about 15 in size, occasionally invites authors it is reading. Given that the first three books the club read were by Caro, Ginsberg was understandably nerve-racked when the author agreed to speak at one of the club’s meetings.