The best night ever...is anything ever as good as you imagine? 

Spike can't come in cause they're getting dressed. References to ponies being naked always just amuse me. 

"Oh Fluttershy you're such a loudmouth!" 

Pinkie just does a stage dive without knowing where she's going to land. So Pinkie. 

Prince Blueblood is another character we should have seen more of. I know there was a comic where he helped Shining Armor with some diplomatic stuff. I assume Celestia adopted him as a nephew like Cadence but being royalty went to his head.