I was taught that you NEVER have anything else after taps. It was disrespectful (?). So we always did our "fun" stuff just before, including the Goodnight like you described, our "birthday song", the squeeze-all those cutesy endings the girls like.
At the end of each meeting in Guides, after we sang taps we would hum it and then the leaders would say Goodnight Guides and we would say Goodnight Leaders.
Jen Alexander, Mapleway Area, Waterloo Division:
When I was in Guides, we would slowly break our circle by taking one step back and yelling "G", then another step back and yelling "O", etc., until "Good night" was spelled out. We would then yell "Good night!"
Jean Reid, Janetville and Toronto, Ontario:
Following taps and a moment or two of silence, we quietly said "May the Lord watch between me and thee while we are absent, one from the other." Following another few moments of silence came "Goodnight, Guides" ... ah, memories!