The ending of the main story line for "Cheers", not a large number of resolutions or clever insertions.
When "The Mary Tyler Moore Show" set a standard for the "great finale", tons of shows later rushed into the fray to be "significant" at their close. The "Cheers" installment falls a little short for me.
To me, it's a little too bad as I really liked this program as a high mark for ensemble comedy. In the final analysis, too much happens early here, and not enough happens late. Diane is back, but the scenes on the airplane are pat, the "voices" heard over the intercom echo something fans have heard and heard and heard before. Rebecca could have been a great wild card in this story, but she is packed off with a new fiance without much treatment. But to me, where the episode is most weak is the final 20 minutes - despite some mediocre wrap-ups, a LOT of time is spent on Cliff's "history is made by men in comfortable shoes" bit, not terrible but not much of a final send-off all-in-all. If Norm, Carla, Cliff, Frasier, and Sam are really smoking cigars and wondering about the meaning of life - there could have been something more on the mark to wind it up.
Sam's final closing words, "we're closed" is pretty appropriate, but in a lot of ways this installment closed far earlier.