There has been much debate as to whether The Muppet Movie or A Muppet Family Christmas is more of a Jim Henson victory lap. In any case, both are Crowning Moments for everyone involved and both feature a fantastic moment at the end that is somewhere in-between this and Crowning Moment of Heartwarming:
"Here's to the lovers, the dreamers, and you!"
Mad Scientist/ Mel Brooks: Say Goodbye to the frog, pig! Piggy: Why should I? Mad Scientist: Cause in about ten seconds, he won't know you from kosher bacon! Piggy: THAT DOES IT!!!!!!!!!!!!! (Bursts out of her bonds and proceeds to whoop ass.)
From a production standpoint, Kermit riding the bicycle. Decades later and people are still impressed by the puppetry work.
In the same vein, the duet between Kermit and Rowlf. It fulfilled something of a desire of Jim Henson's that would've been impractical on The Muppet Show (as he performed both characters and the average episode had a obviously tighter filming schedule).
None other than Orson Welles providing the film's final cameo, fulfilling all of Kermit's dreams without even needing to see any of his act.