I think it would make most sense to have it in a location where there are the most YTers. Because of this, I would think NYC would make the most sense.
Some of the places mentioned have been great, but to be blunt, not everyone (including me) is going to be interested in coming to some random location where the only thing of interest is the meet up.
ETA: With so many people living in within say a 3-4 hour drive of New York City I'm sure a lot of people could just make a day trip out of it. If you don't have to spend hundreds of dollars on lodging, I'm sure you'd be more tempted to come.