For me I belong to our local Anime Club so I'm the one who sets up all the monthly photo shoots. This way we kill 2 birds with one stone one I get to do a shoot with folks who I've been working with for a months and second we always have a new location example this months shoot will be this Sat at The National Zoo in DC the kicker is we are going to do it after dark during Zoolights. Allot of the cosplayers have decide to bring their best Cold Weather Costume something that they usually don't get to wear much.
I guess I say if you know of a local Anime Club join them find out what the group is doing for shoots. I know that in our group I have a few request for shoots a week from members who are getting their costume done and want to have pics done before the net big Con which for us will be Katsucan.
As for Con stuff I'm not sure how many folks go down tot he Con sections and look around at photo shoots that are being set up by the different cosplay folks but if your interested in doing Group Stuff check out the Con that your going to and see what the groups have planned. I know that I mainly now shoot just group stuff at the Cons I go to and I find it fun because you can get some real great group action stuff.