DCATravel:
I have had excellent success at this property, although I am a Diamond. First, if you are coming in on a weekend night, you usually would have a better chance as business travelers are gone for the weekend for the most part. Second, I take it that the DCA indicates that you are from DC, and you may let the staff know that you live relatively close by so if your stay is as wonderful as you have heard others have had, you certainly will make it your buisness to be back. Third, if you are well on your way to Diamond this year, perhaps you will have had a sufficient number by the time you are there to verify that claim to them. Fourth, you should do as UpgradeMe says and ask if it would be possible to experience a suite for your -- I assume -- short stay, so that you can know what would be in store for you should you attain Diamond, as you have heard that this property treats its Diamond members quite well -- which it does. Finally, I assume, that this might be a paid stay, if so, then you should have "received" electronically an upgrade Cert after every third stay. You could always use it if necessary. Finally, I would indicate to them that you intend to take at least one meal at the hotel -- the breakfast in the Grand Domed dining room is both great and inexpensive. That also may help.
Also, the Jazz Club Zanzibar Blue which is at the base of the building, but unfortunately unconnecte in any other way to the hotel is great.
Enjoy your stay and let us know how it turned out!