Oh, for the record, just so that I don't get derided for inviting a discussion but not participating in it up front: My leaning at this point in time is to ignore the issue of prostitution and focus instead on sex crimes, sex trafficking, and sexual exploitation. In other words, focus the light of the law onto the (usually) males committing these crimes rather than the (usually) females who may facilitate the activity. One of the arguments in favor of legal prostitution that I find more compelling is that focusing on prostitution itself is inherently punitive toward females. Usually, when it comes to issues of a sexual nature, the terms of argument turn on what society should do about females--usually to their detriment. I've found it very useful to keep a rule in my personal RAM which states that, whenever I detect an argument which is imbalanced like this, I'll look for ways to solve the exact same problem by focusing on the male side of the equation. That can be pretty effective, and, together with the fact that prostitution can be a major source of income for females, these two arguments are why I lean in favor of permitting legal prostitution.
It's worth noting, however, that the legal system in America is different from that in much of the rest of the world, in that America anything which is not expressly prohibited by law is legal. To my understanding, in much of the rest of the world it's the other way around: Only that which is expressly permitted by law is legal. This other way of reckoning would affect the prostitution question by forcing the issue, which, I bet you, is part of the rationale as to why prostitution is explicitly outlawed in some of the liberal European nations: Prostitution is an ugly industry, and explicitly legalizing it is different, in ethical terms, from tacitly allowing it.
