One thing that I love about "Wings" is how wild, bizarre characters will pop up from time to time (Officer Colleen Thomas, Sconset Sal, Dr. Lenny, etc.)...and the show's writers have the self-discipline not to over-use these characters.
Some sitcoms have taken wild minor characters and elevated them to "star" status...and many times the show's high level of mature, well-written humor was ruined in the process.
"Wings" didn't do this....they brought in these wild "over the top" characters for one-shot (or maybe "two-shot") appearances for us to enjoy, but they didn't try to shoehorn them into the series as cast regulars...and the show was better off for that.