One mystery detective show I've not seen since the original '80s run and recently revisited is Remington Steele; a local digital side-channel has started running it as part of "Me-TV" programming. And it's held up quite well. The leads are great, the premise is strong, the characters are real and funny, the plots are sometimes a little rushed but usually solid. Stephanie Zimbalist is terrific, never overselling her detective's hardness and handling the light comedy effortlessly. I never understood how she didn't become a major star.
I'm actually surprised that nobody has tried rebooting REMINGTON STEELE yet. The premise would lend itself to a big-screen version.