The opening of 42nd Street gives me goose bumps everytime
I also enjoy the dance breaks during Springtime for Hitler in The Producers along with Stro's ingenius scene changes
Jellicle Ball is a huge DUH
Snuff that Girl's dance break is hysterical
And since my favorite show right now is Avenue Q, I have to add how the puppets dance during the "da da da da da" part in It Sucks to be Me and Princeton's dance with the moving boxes during Purpose always put a smile on my face