Cheers/YMMV

"Carla: I just miss him so much."
 * Alternate Character Interpretation: Remove the laugh track live studio audience, and you have a pretty sad story of a hardcore alcoholic, Norm Peterson, who neglects his work and family obligations to spend 12-14 hours per day in a bar.
 * Norm has admitted to Sam and Diane he's lying about neglecting his wife. Any time his marriage is threatened, Norm becomes desperate to keep it together. It's also hinted that Vera is quite beautiful.
 * Not to mention the dangerously paranoid, delusional, sexually dysfunctional and possibly matricidal postal worker Cliff Clavin, who stalks TV personalities, writes threatening letters to politicians and has an unhealthy obsession with conspiracy theories and government plots. Hell, even WITH the laugh track the character is slightly uncomfortable to watch at times.
 * Character Derailment: After Diane left, all traces of Sam's problems vanished. His alcoholism became a non-issue, his womanizing was more of a joke than when Diane was zinging him for it, and even Word of God pointed out after the show had ended that the series began to depend less on clever writing and more on physical humor. This was pointed out in the documentaries in the DVD releases.
 * Ear Worm: "Sometimes you wanna go where everybody knows your naaame..."
 * Ensemble Darkhorse: Al, played by Al Rosen. He first appeared exclaiming "Sinatra!" in one episode, and was such a hit with the writers, he was given more and more punchlines by the writers. He was later referenced in Frasier episode Cheerful Goodbyes when Cliff told Phil, "You've always been there for me, Al", and Phil retorted, "I'm Phil. Al's been dead for fourteen years, you dumb son of a bitch!"
 * Freud Was Right: Frasier and Lilith, naturally.
 * Funny Aneurysm Moment: One episode saw Sam give a radio interview in which he makes disparaging comments of Diane. She gets mad. He gets apologetic. Years later, recurring cast member Jay Thomas gave a radio interview in which he made some disparaging comments about Rhea Perlman. She got mad. He got fired.
 * Jerk Sue: Carla could theoretically qualify, in that her abusive, cruel, hateful behavior would have gotten her fired (and/or arrested) practically anywhere else, many times over. Somewhat justified in that she's effectively Sam's best friend, but it still makes no sense that Sam thinks Diane drives off customers but that Carla apparently doesn't, despite Carla apparently actively trying.
 * Mary Sue: Sam's brother Derek, a successful (and supposedly handsome) lawyer, who stops by the bar at the end of the first season spends the entire episode offscreen in the backroom wowing the regulars with his singing, piano playing, tap dancing and pool tricks. Over the course of the night he gets the unemployed Norm a job at a high end accounting firm, teach Coach fluent Spanish, seduce Diane into going away with him on his private jet and have all the customers fight over who should get the pleasure of buying him a beer. All while Sam stands alone at the counter in the front room having to hear from anybody who steps in how terrific his brother is. Sheesh, no wonder he has an inferiority complex.
 * On the other hand, no one benefited from Derek, like Norm, in the end. When Derek leaves, the bar expresses disappointment. Derek may have talents, but Sam has friends.
 * Rescued From the Scrappy Heap: Rebecca, once she switched from Diane II to the neurotic mess she was for the rest of the run.
 * Retroactive Recognition: There are several in the series.
 * Carla's daughter who gets married is played by Leah Remini (King of Queens).
 * Brent Spiner appeared in a two part episode.
 * Frasier regulars Peri Gilpin and John Mahoney appeared in separate episodes.
 * John Mahoney plays Sy Flembeck, a jingle writer - whose skills wind up being criticized by Frasier. In Frasier, Martin helps Frasier write a jingle.
 * Peri Gilpin plays a jaded reporter who has all of the same mannerisms and snarkiness as Roz.
 * Kate Mulgrew was a romantic partner for Sam in a three episode Cliff Hanger.
 * Nancy Cartwright appeared as Andy-Andy's fiance. Fellow Simpsons (and The Critic) castmember Doris Grau had a few appearances as Corrine.
 * Michael Richards appeared as a con-man who tried to bilk Sam out of his bar.
 * Thomas Haden Church appears in Death Takes a Holiday on Ice.
 * A studly blond Kevin Conroy appears in the same episode.
 * Diedrich Bader appeared as a snarky waiter in episode Sammy and the Professor.
 * The Scrappy: Diane. Oh god, Diane...
 * Tear Jerker: The Dream Sequence after Diane leaves for good in "I Do and Adieu", where Sam imagines what might have been with the two of them as an elderly married couple.
 * Sam's tearful goodbye with his imaginary son. The son says "see you in a few years," but Sam never remarried to date.
 * "Sorry, we're closed." (*adjusts Geronimo picture*)
 * In "Pitch It Again, Sam," Sam gets a chance to pitch in an exhibition game. At the stadium, Sam comments that the only thing missing from this great opportunity is Coach. Carla tries to do an impression of Coach to motivate him, but she winds up crying - twice.