I’m a fan of the 1970s to 1990s detective show Columbo, and I’d like to introduce my girlfriend (who’s never seen an episode) to it. Which episode would be best for a newcomer? It should be a high-quality one to whet the appetite for more, but it should also be representative of the overall style of the show. My personal choice so far would be season 1’s Suitable for Framing, which has the most stunning final “gotcha” moment I can think of.
“A Stitch in Crime” with Leonard Nimoy is really good. So is “The Most Crucial Game” with Robert Culp. My personal favorite is “Forgotten Lady” with Janet Leigh, but it’s unusual in that Columbo lets the murderer get away . Another unusual one is “Troubled Waters” with Robert Vaughn, which takes place on board a cruise ship. Jack Cassidy was in several episodes, but his best performance is in “Now You See Him.”
The episodes from the '70s are generally the best. I wouldn’t show your girlfriend the ones made later until she’d seen all of the earlier ones first.
Probably any of the early episodes, except maybe the first 1968 pilot, Prescription: Murder, since the Columbo persona, while mostly there, hadn’t quite been developed yet. I don’t think he even wears the raincoat. Maybe start with the second pilot, Ransom for a Dead Man.
Murder Under Glass from season 7 might be a good one if you want to start your girlfriend on one in the middle of the series, when the whole shtick is really cast in stone. That’s an episode I had remembered from its first run as a kid-- there’s a scene at the end where the murderer asks Columbo “when did you first suspect it was me?” Columbo says “a few minutes after meeting you.” The murderer, who of course is very cocky and thought he had committed the perfect crime, is astonished “That can’t be true!” When Columbo tells him why he suspected him so soon, it’s an “aha” moment that made kid me go “whoa”. It made me realize that no matter how smart you think you are when committing a murder, you always forget something. It was a big influence on my decision as a grownup not to ever murder anybody.
Columbo episodes were available on one of the streaming services I subscribed to a while back so I watched Murder by the Book, the first episode of the first season (after two pilot episodes), partly because it was directed by Steven Spielberg.
Negative Reaction is probably my favorite: Falk is as good as ever, and Dick Van Dyke is terrific at selling the key bits of business, and even the filler is actually pretty entertaining,
Titles escape me at the moment but the one with Jack Cassidy as the magician and the one with Richard Kiley as the deputy police commissioner.
I can’t recommend any specific good ones (maybe the one with Ross Martin? or Johnny Cash*?) but I could tell you with ones to avoid! 
The Lawrence Harvey one is particularly bad.
*I like that one, but i felt the ending should have been a bit different. I think Johnny should have killed Columbo and left his body in the desert, and lived happily ever after. That was stupid move by Columbo. In for two murders, in for three. Even if the third one is a cop. The lt. could have been wrong, even with his keen insights into the criminal mind!
That was a good one, with an uncharacteristic performance by Van Dyke playing a grade-A asshole.
But the ending always bugged me: Columbo gets him to identify the camera that only the killer would know because he needs an original of the kidnapping photo and says to look at the negative in the camera. Why would the negative still have been in the camera when the picture had already been developed?
I thought the idea was it’s an instant camera, such that a kidnapper could just use a gloved hand to grab the cheap Pops-Right-Out-Of-A-Polaroid picture and wrap it in a ransom note — but the negative is still in the camera after you do that, if you want to do other stuff with it. I thought that was a genuine feature of 1970s available-to-consumers photo tech.
Maybe so. In that case, it is a great intro episode-- I like the ones where Columbo not only plays dumb, but does something that seems like a dumb mistake on Columbo’s part, but is really a trap he’s set up.
Blueprint for Murder has a similar twist-- Columbo has a huge building pylon on a building under construction dug up, because he supposedly thinks the owner of the construction company buried a body under there. When no body is found, it looks like Columbo has made a terrible, expensive mistake-- until the owner tries to put the body in the newly dug out pylon, which was his plan all along, but Columbo has figured it out, and is there to arrest him.
“Now You See Him” and “A Friend in Need,” respectively.
The same camera was featured in an episode of MASH. (Klinger was suspected of stealing one.) It was very high-tech back in 1953.
“Any Old Port in a Storm” is highly regarded in general and a must for any oenophile, as well as the exceptional performance by guest star Donald Pleasance.
Stranger
Though it does take some effort to get around the thought of dressing a corpse in a wet suit after he’s been lying in an overheated cellar for several days. 
I find it hard to believe that either Cash or Columbo could find the spot where the evidence was hidden in the middle of the forest at night. Anyway, I haven’t seen that episode in decades. I think it’s been pulled from the lineup for one reason or another.
Getting any unconscious body into a wetsuit would take exceptional dressing skill but at least one that is beyond rigor will be compliant, and at least the leaky fluids would help lubricate the process. One could understand why Adrian would fling his precious wines into the ocean even if they weren’t spoiled by heat, though.
Stranger
Leaky fluids, yeccch!
ISWYDT
Whichever sub channel was showing Columbos (Sundance?) showed it a lot.
I’ve seen the last couple of months on whatever streaming channel I get it on, maybe Cosi?