Sitcoms had been done before built around widowers and their kids. The difference between those and Empty Nest was that on this show, the kids were all grown up and working for a living, coming home to give their father some company after their mother passed on.
Empty Nest was a spin-off from The Golden Girls that went to series the second time around. The first backdoor pilot, in 1987, featured Paul Dooley, but it didn't get the reaction that Touchstone Television & NBC wanted, so back to the drawing board they went. The final product reunited stars Richard Mulligan and Dinah Manoff with their bosses from Soap, executive producers Paul Junger Witt & Tony Thomas, and series creator Susan Harris. The show was built around Mulligan as widowed Dr. Harry Weston, whose only companion at the start was his dog, Dreyfus. Soon, Weston's daughters (Manoff and Kristy McNichol) come home to set the stage for the series.
Isuzu pitchman David Leisure was cast as Weston's neighbor, Charley, who, based on the description I read, would routinely show up in the Westons' apartment unannounced, a la Cosmo Kramer (Michael Richards) on Seinfeld, which came along roughly around the same time. Some plots centered around Weston at work in his clinic with his nurse (Park Overall). In season 6, Dr. Weston had retired from his practice, but now had a new assistant (Marsha Warfield, ex-Night Court), although Overall's character would soon return after she'd left the clinic. In adddition, Estelle Getty joined the cast full-time, reprising her Golden Girls role as Sophia. Golden Girls had ended its NBC run in 1992, and made the ill-fated move to CBS, where, as The Golden Palace, it had ended after the 1992-3 season.
Let's take a look at the pilot.
Kristy McNichol had left the show after 4 seasons, only to return for the series finale in 1995. Disney holds the rights to the series, but good luck finding it on cable these days.