While it's still too early to talk about this, what days would be good for a gathering? I would say that since the major cosplay gatherings and concerts occur on Day 2 and 3, I would say that Days 1 and 4 are the best days for this gathering, especially Day 1.
Pick the days you think a gathering should occur (I made a big mistake in the choices. Just assume Day 1 is the first choice (Friday), Day 2 is the second choice (first Saturday), Day 3 is the third choice (second Saturday), Day 4 is the fourth choice (Sunday)).
Facebook Cosplay Page
Future Crossplays/Genderbend Cosplays
Future 2013 Cons
Anime Boston (Tobiichi Origami (Crossplay), Akito, Izaya, Len)
AnimeNEXT (Gaul, Senbonzakura Len, Riki (Girls School Uniform), Itsuka Kotori (Crossplay), ALO Kirito)
Anime Expo (Sandplay Len, ALO Kirito, Genis Sage, Kotori, Riki)