Journal 15
I do think this is a case of entrapment. Portia is trying to trap Shylock in his bond by trying to convince him to take money instead of the pound of flesh. She knows that he wont take it over his warped view of "justice", but she baits him with it. She doesn't seem surprised when he says no because she knew it would happen. It's almost unfair to Shylock that she is doing this, since he is playing so well into her trap. She then states that he can have his pound of flesh, but he can only cut exactly one pound or else he will violate the laws of Venice. At this point you can tell he has been defeated both mentally and physically and try's to take the money, but it's too late and Portia says no. She humiliates him, which was her goal from the beginning.
Humiliation
I agree with your point that Portia's overall goal was to humiliate Shylock. It was easily done as he just walked into it. He was easily trapped in Portia's web.
Smarter than we think
Portia is definitely smarter than she appears at first in the play. She has a head for getting what she wants and humiliating people along the way to get it. These traits are definiteally unexpected for a female character in Shakespeare and should be seen more often in them. It's less the fact that Shylock is stupid but more the fact that Portia is smarter than people give her credit for.
A change in roles
It is kinda ironic that Bassanio, who is love with Antonio (a man), would fall in love with a woman who displays such masculine traits. Sometimes Portia is more of a man than any of the people in this play. She even dresses up like one. I guess Bassanio has a thing for masculine people. I don't know if Shakespeare planned it this way, but the seems to be some role reversal in this play. He takes a social norm of men playing the dominant role and gives it to a female character. No matter what you think of Shakespeare, it is obvious that he loved to mix up their common social standards.
another level
Plus, the character playing Portia was initially a male playing a female, so we get a male who is playing a female who is playing a male. Bradley
Bradley