So many great choices already, you guys! I concur with so many:
Columbo (the gold standard, imo)
Kolchak: The Night Stalker (Dave in the Valley: The one you remember is the TV movie sequel to the first TV movie, "The Night Stalker," called "The Night Strangler," and it took place in Seattle (Chicago was the setting for the TV series, which came a little later). Yeah, the underground city thingy was neat.
McMillan and Wife (not nearly as well made as Columbo, but not without charm)
The Rockford Files (c'mon, admit it...just reading the title made that great theme start playing in your head, now didn't it?)
Hart to Hart (totally cheesy in a very '80s way...embarrassing, but enjoyable)
Dragnet (gotta love those late '60s episodes...I've rhapsodized before about this show, so I won't do it again!)
Car 54 and
Barney Miller are great, too. Cops and families of cops still say Barney Miller was THE most authentic cop show ever, Hill Street Blues and NYPD Blue be damned. They consider the '70s sitcom to have been a much more accurate reflection of day-in-the-life police work than either of those two "gritty" Emmy-anointed programs. Go figure. And I'm sorry...was anybody NOT teary-eyed when they did the tribute show to the recently departed Jack Soo? I'm SO sure.