Do you know what's great about cosplaying school girls? You can recycle that costume to be almost any other female character from that show. :) Usagi can do Ami easily with a different wig, any Ohtori girl can be any other Ohtori girl who's not on the student council, and you can be just about any character from the Card Captor Sakura universe just by changing your hair.
When I originally bought this uniform off of eBay, I had an informal poll in my LiveJournal to let my friends decide whether I should use it for Tomoyo or Chiharu. Tomoyo ended up winning, but my then-friend Louis had been campaigning pretty hard for Chiharu, because he's got a "thing" for pigtails. Since Tokyo Festa occurred in a week of terrible weather, and since I was now dating Lou, I decided to give Chiharu's character a shot, as her hair is much easier to keep nice. She's a lot of fun, and wonder of wonders, I actually remembered to wear the turtleneck underneath (a feat I still haven't managed to accomplish for Tomoyo), but I doubt I'll do her again, as she's pretty unrecognizable by herself, and if I'm going to be with a group, I'll probably choose Tomoyo again anyway.