I think it depends on what everyone wants to do. I think that the Jersey thing was perfect, because people did different things during the day, while others just came for the company.
Personally, I think that if you're going to get together, then just get together. I don't think we need a big convention or other distraction. If we were to do it in Manhattan, then there's certainly enough to do there (Sopranos tour, Ellis Island/Statue of Liberty just to name a quick two) that would be Ganster related. And like you said, DC, there are certainly very few cities that offer more in the way of restaurants, etc.