When I was doing all that research on WKRP in Cincinnati music changes a few months ago, one thing I noticed that I hadn't really noticed before was that the show had a pretty good track record of keeping up with changing musical trends. It was only on the air for five years, but you can actually hear how the music they're playing in 1982 is different from what they're playing in 1978, and this despite the fact that a lot of the songs are Golden Oldies. (As the series went on it became sort of a running theme that the disc jockeys didn't really care what the format was supposed to be, and would randomly pick any song in any style from any era.)
Sometimes the writers and the two actors playing the DJs (who picked much of their own music) would pick recent songs that weren't hits at the time, but would become hits later. In the second episode, the most prominently-featured song is -- or used to be -- "Old Time Rock N' Roll" by Bob Seger, a new song that was popular with real-life DJs at the time, but wouldn't really become a standard until Risky Business featured it five years later. And in the "Real Families" episode, which aired on November 15, 1980, you can hear a snippet of Once in a Lifetime by Talking Heads, which came out only a month before, and again took a few years to really catch on:
By that point in the series some of the producers were underscoring entire scenes with rock songs, on the assumption that in a radio station the radio would actually be on in some of the rooms. So the most surreal episode, "Hotel Oceanview" (basically an expanded version of a Second City sketch by the same writer), had its final scene underscored with the then-current "soft rock" hit, Christopher Cross's "Sailing."
The sense of period is not one of the most important casualties of all music changes, but still, it's a shame to lose those subliminal indications of what was new in popular music at the time of a particular episode.