Ron, I too like Carly Simon, but when she's singing her pop/rock/folky stuff as opposed to the standards which I don't find her voice suited for...unlike I find Astaire's voice, which despite its flaws, knew how to put those songs over...It's why not only Porter loved him, but also Gershwin and Berlin. The wrote songs specifically for his vocal stylings.
I don't need perfect voices...just voices that know how to serve and sell the song. Jimmy Durante singing Young At Heart can be incredibly moving.
A modern singer who I think knows how to sing a standard is someone like K.D. Lang.