I agree that, while the Levee has potential, it needs to have some real home-run hitters and so far it doesn't. I had thought the Cheesecake Factory would be a good fit, but they slapped it in Kenwood. A Rainforest or something like that would help. Bottom line is, it needs more or else it will fail.
As for the Riverfront, I agree that a nice park would have been the best bet. Other cities have them. We do not.
That said...
I think we're forgetting something in all of this. Cincinnati, while I love it, is rather stoic in its ways. And what I mean by that is, we can put all kinds of "trendy" things left and right; at the end of the day, we're still Cincinnati, and we are anything but "trendy." The people who live outside the city don't want to come into the city. And I don't see that changing anytime soon.