It would be nice to be able to send a message again by hitting a button or menu item. Currently when I have to resend a message because a customer didn't receive it, I use my iPhone to "Send Again." If I want to change it significantly, I will change it slightly on the iPhone, then cancel, then save to drafts. Then I can edit it and send it from drafts.
In SM, I can move it from sent items to drafts, and then send it, but then I lose the original in the sent folder.