My best friend and I have an ongoing debate (in addition to the appropriateness of suede sandals in the spring & summer) about where your heel should hit when wearing sandals. She adamantly believes that the "curve" of your heel (the part moving towards the achilles tendon) should not hang over the back of the sandal. I, however, believe that the "curve" of your heel can hang over the back of the sandal as long as your heel does not hang over the back of the sandal.
I hope you all understand what I'm trying to say. I'd post pics but 1) I can't post pics via my blackberry and 2) I don't think my heels are quite camera ready (nothing a little lotion can't handle).