...I'm fairly positive that Johnny Carson switched to having guests seated in a chair to camera left of his desk almost immediately, and Jack Paar didn't bother using a desk at all on his prime time Jack Paar Program. On Jack Paar Tonite, he used the opposite of Carson's arrangement, sitting at a desk and his guests in chairs to camera right of that desk. Merv Griffin used the desk and had guests seated next to him at it on his Westinghouse show; when he moved to CBS, the desk was gone and Merv sat with his guests in one of a row of chairs across the stage. Merv continued in this mode on his Metromedia show until around '80, when he started copying Carson's arrangement with a table in place of the desk. When Steve Allen started his Westinghouse chat/variety show in 1962, he had guests sitting to camera left behind the same desk, and on his 1968-71 Filmways show he had two rows of chairs extending forward from his desk. Dick Cavett also copied Carson's arrangement on Good Morning and the first year or so of the nighttime Dick Cavett Show on ABC, but eventually junked the desk and joined his guests around a coffee table. Tom Snyder also utilised the coffee table approach on Tomorrow; when he returned for his run on CNBC in '93, they sat him and his guests behind a trapezoid-shaped table which Snyder hated, and the coffee table was brought back to stay for both the lion's share of the CNBC run and the first years of The Late Late Show. Coffee tables were also used by Mike Wallace on both Night Beat and The Mike Wallace Interview (I don't recall what the pattern was on PM East), David Susskind, Arsenio Hall and on Politically Incorrect with Bill Maher and Irv Kupcinet's Kup's Show. Later with Bob Costas had only a couple of overstuffed chairs, with Costas in the one at camera right. While on ABC, I believe Les Crane had himself and guests in chairs and the audience in the round. I don't have any visual memories of The Joey Bishop Show or The Late Show with Joan Rivers, and I never saw David Brenner's syndicated talk show of 1986-87. Of course, for a while everybody in daytime talk -- Phil Donahue, Oprah Winfrey, Sally Jessy Raphael, Maury Povich, Geraldo Rivera, Jerry Springer, and Danny Bonaduce -- had their guests on a stage while they ran around the audience to field questions. Morton Downey Jr. had his guests on a stage, his own base to camera left and audience question podia facing both. It seemed as if Stephanie Miller's arrangement switched every couple of weeks during her half-season syndicated run. Ellen DeGeneres is a coffee table gal nowadays. Everybody else I can recall -- including Wil Shriner, Rosie O'Donnell, Caroline Rhea, Bonnie Hunt, Alan Hamel, Alan Thicke, Jerry Lewis, Greg Kinnear, Craig Kilborn and the current network late night crowd -- pretty much copied Carson's arrangement. As to the why, I don't think there's much of a reason other than to either distinguish themselves from the other current productions or to try to copy the feel of Carson's show...