Well, this thread is huge, so I didn't read very much of it, so forgive me if everybody's already saying this, but considering that they've covered "New York," "Miami," and "Los Angeles," I'm surprised that they haven't gone to a Vegas-esque city yet.
EDIT: I did notice on this page, some talk about a female protagonist. I think it would be a good idea, actually. It's a sandbox game, so you can be as floozy or as rug-munching as you want her to be. Or maybe some of us will actually play her as a respectable femme-fatale.

But I think it would be hilarious if you had the option to make money by whoring yourself out, and then, when you get out of the car, the driver gets out and tries to kill you to take his money back.
Of course, I find this funny in the sense of gamers' karmic comeuppance, and not because I think killing hookers is hilarious. Necessarily.