I missed the comment on riffing... I have to say I'm very fond of a good riffer.
Unless you're Jennifer Holiday or have a similar voice (ex. Miss Skinner) don't try it at home. But hey, I'm all for the riffing if you're physically capable of doing so. Attempting and failing can be painful to the ears, but if you're a big black girl or sing like a big black girl, then by all means, please riff!

And clearly it's completely inappropriate for some songs... but if it works, it's great. I'm not talking about the Mariah riffing... I'm talking about the good ole fashion, J-Ho kind of riffing... that's some good **** right there!
"You! You are the worst thing to happen to musical theatre since Andrew Lloyd Webber! And you, well, I just plain don't like you."
~Stewart Gilligan Griffin