What a great question! I absolutely adored pondering this! Juliet absolutely is shrewd and knowledgeable in all things men! Further, I adore any actress who actually plays her in that way. My first example isn't absolute where the actual text is concerned; however, it can certainly be performed in this way. Claire Danes, for example, does a superb job with this line:
What's Montague? It is nor hand, nor foot, / Nor arm, nor face, nor any other part / Belonging to a man. (2.2.42-44)
Make no mistake about it, there is only one real area that makes a man a man. Is Juliet being shrewd here? Heck, yes! A mention of genitalia without the mention of genitalia! Female genius! In regards to her litany of boring body parts, it's the equivalent of a guy going to the drug store and buying a million other things before the box of his wife's tampons! Ha!
My next example has more to do with Juliet's knowledge of men and of the courting rituals of the time period:
Or if thou thinkst I am too quickly won, / I'll frown, and be perverse, and say thee nay, / So thou wilt woo; but else, not for the world. (2.2.100-102)
Juliet knows that usually a girl would be incredibly modest, often playing "hard to get" as the man "calls" continually, often bringing gifts, hoping to eventually win the young lady's hand in marriage. However, Juliet knows that her previous speech (with Romeo spying on her) "gave thee mine before thou didst request it." In other words, Juliet knows that Romeo already heard her vow of love, so there is no reason for him to woo, . . . unless he insists upon it (which he doesn't, of course).
In thinking about my final example, I always have to laugh:
If that thy bent of love be honorable, / Thy purpose marriage, send me word tomorrow, / By one that I'll procure to come to thee, / Where and what time thou wilt perform the rite. (2.2.151-154)
What a shrewd little miss!!! Juliet is dictating everything!!! Here she becomes the dominant force in this relationship! First, there is the fact that she is being pressed to leave by her nurse, so there is no real time for Romeo to object. Second, she puts pressure on Romeo to fly to the actual marriage (instead of wooing). Third, she makes him decide by the following day. Fourth, Juliet herself decides both the place and the time for the ceremony! Ha! Shrewd wouldn't begin to describe Juliet here! I think the reality show Bridezilla would be more appropriate!