What qualities makes a lady "classy"

The six pillars of character are a good place to start:
Trustworthiness, Respect, Responsibility, Fairness, Caring, Citizenship

As well as: Politeness, Consideration, Selflessness, Confidence, and Strength.

OR, if you prefer
http://www.wikihow.com/Be-Classy

I love these types of Q's.
To me, a girl who loves to facilitate her man - who adores him, and makes it easy for him to reciprocate.
A girl who realizes that personal presentation and looking after herself is instinctively, very important to the male response - more important than whether one was born naturally physically beautiful - although natural beauty can help, of course.
A girl who is warm and affectionate and non-judgmental and who loves to be around her man, and inspire him to greater heights; who is virtuous, lovely, honest, true, benevolent and believes in doing good to all - who seeks praiseworthy things and attributes, is kind, diligent and responsible.

Modesty, class, good conversationalist, won't kiss and tell, likes good clean fun, doesn't obsess about sex (see last entry), enjoys a real good time on the town, grace and style, charm and wit, good but not gaudy fashion, social acumen, makes heads sway not because of how her body looks but upon the way she carries her self; these and many other facets make a woman a true gem :-)

Billy Joel put it this way!

A woman who respects herself, and has confidence. She has a hard to define quality.

The way you wear your hat. The way you sip your tea.