I haven't seen the numbers myself (although I'm dying to) but I've been told that $$ wise, people from visiting cities contribute more money to the team than the Baltimore area. (I'm assuming they are counting Northern MoCo as part of the DC market) But seeing how they track purchases by zip code it raised an eyebrow for me.
Last I had heard was that the finalists for the classic were Nats Park, Fedex, and Byrd Stadium (or whatever they call it now).
Capital One Field and that would just be an awful idea. I guess that's a step up from RFK.