Well, I will be dressing up for the event and will gladly join any group photo that welcomes me and that doesn't conflict with my schedule...
I am planning on four different costumes for the event...
In general I plan a generic, and not overly accurate, TOS red dress for Friday.
A 7 of 9 inspired look (maroon jumpsuit) for Saturday
And finally a TNG/Deanna Troi (green dress) for Sunday
Oh and I almost forgot... Orion slave girl for the Klingon Party (possible the TNG one as well)
I don't know if any of these looks are in keeping with what you want to create in this group photo, but if you are interested, and set a time and place, I'll gladly participate (schedule allowing)