There were a lot of costumes at C2E2. Many people dressed as individual characters and went to have fun with their friends and a lot of people matched a friend to make a couple cosplay. The best though are the groups of friends and family that play an entire cast of characters. A group takes a lot of effort because you want everyone coordinated and you want to avoid duplicates.
A family is probably easier to make a cosplay group out of because everyone is (generally) under the same roof and the costuming is usually only made by one or two people. When a large group of friends manages to pull off a group cosplay, that is an amazing feat. Here are just a few of the group cosplays that were at C2E2 this weekend:
Honorable mention goes to the Indiana Jones Group with their Ark, unfortunately that is when my camera had chosen to die and my phone did a horrible photo.