I agree about Amneris in "Aida". She has a much more challenging arc than Aida or Radames in that show. I was privileged enough to work with an incredible Amneris who brought out all of the comedy in Amneris' early "bimbo" scenes without parodying them. By the judgement scene and the last number, she had undergone incredible suffering (keeping us with her every step of the way) and become a strong, unyielding force of nature. As a friend put it, "She starts out Jessica Simpson and ends up Margaret Thatcher."
There's also a great little campy show called "Ruthless"--it's not intended to be realistic, but the main character, Judy, starts as a cheery, empty-headed, trilling Stepford Wife and metamorphoses by Act Two into a grasping, belt-it-out, Broadway diva. Meanwhile, her adorable curly-haired daughter Tina (a takeoff on Annie, Baby June, and every other Broadway brat) goes from a disgustingly sweet model child to a monstrous, coldhearted killer. Certainly startling.
I ask in all honesty/What would life be?/Without a song and a dance, what are we?/So I say "Thank you for the music/For giving it to me."