Personally for what is appropriate for my current age and occupation as a full-time student, I identify with Hepburn more than Dietrich. I tend to associate Hepburn more with daytime wear and Dietrich with the night. I simply only need to be comfortable (though preferably still looking good) for class. Certainly depending on the woman herself, can choose to have an even mix of influences from the two icons or even just Dietrich. Furthermore, I just adore how unfussy (though not unkempt) Hepburn is. Though now the "effortless" style is all the rage, she was modern and way ahead of her time to be so carefree and relaxed in her approach to dressing. There's no calculated false pretenses, but only out just to have fun.
"I never lose sight of the fact that just being is fun"
Via Everyday I Show