The Saturday Post: So Long, Farewell edition

Last night was Bubby's last night at Gramma's house. As he, Baby Mac, and Mommy headed up the stairs to bed, I couldn't help but think of this from the Von Trapp kiddos (ignore the glaring error in name by whomever posted this video on YouTube):

So long, farewell!

Today's fill-in-the-blank:

My favorite song from "The Sound of Music" is _______________.