(WSJ) - THIS PAST MONDAY afternoon, a vast apartment on New York's East End Avenue was swarming with caterers, musicians, bartenders, furniture movers and decorators. The scene in the wine room, by contrast, was relatively serene, as Robert Bohr carefully removed the cork from a 6-liter bottle of 1991 Dominus and then employed a length of surgical tubing to siphon the contents into two 3-liter carafes with the help of his partner David Beckwith. Watching Mr. Bohr sucking wine into the long tube, his colleague Ned Benedict asked, "Where'd you learn to siphon like that?"

"New Jersey," Mr. Bohr replied, crouching on the floor as he directs a stream of Cabernet into the first carafe. Though he was indeed born in Jersey, Mr. Bohr later confided that he learned this esoteric technique for serving whopper formats—which avoids stirring up sediment at the bottom of the bottle—from Burgundian winemaker Jeremy Seysses of Domaine Dujac. It's just one of many skills Mr. Bohr brings to the small group of wine collectors he advises as a partner of Grand Cru Wine Consulting. On that night, Messrs. Bohr, Beckwith and Benedict were taking care of the wine service for a party of 150 people thrown by a client. The room was a showcase of trophy bottles, mostly in large formats—a 12-liter 1955 Conterno Monfortino, multiple Jeroboams of Romanée-Conti—that they'd purchased for the client over the years