I have fond memories of staying at the Waterfront Marriott. I used to be able to get corp rates under $200 and then get upgraded to a corner suite overlooking the water. But I think those days are gone and you're probably out of luck. I have also been upgraded to corner suites at the Ren as well.

By the way, I found a $156 corp rate at the Ren for the dates you mentioned. What's it worth to you?