Well, if I end up going to K-con next year I'll probably bring Sanji (as always XD It's my favorite costume). But I've been thinking that if I can get in shape I really want to do either Margaret or Bonnie, and since they are kind of skimpy I'd want them to be summer costumes for sure XD
But I think me and my friend might do Coby and Helmeppo for Aki-con and I'm so excited :3 I'm almost done with my Marine jacket and I can't wait to wear it around, haha.
Also, if you wanted to add a full list of the straw-hat crew then you forgot Luffy. (And two others that I won't spoil for you since they come in after the Alabasta arc)
Man, I'm happy to see other people wanting to cosplay OP :3