Completely agree! QEII wears tiaras quite well; I enjoy seeing the photos of when she was younger wearing them. My only "issue" with her is that we seem to same ones all the time. I'd like to see her "mix-it up" a bit every now and again. And, Mary in that ruby parue was stunning at the pre-wedding dinner. I honestly believe she is without question the most beautiful Crown Princess (Maxima is a close second and my personal favorite, but one must be objective!).
As for Diana--she wore mainly the Spencer tiara, which was not very elaborate at all--and not terrribly large in height. It suited that short hairstyle perfectly. Perhaps that, and the headaches, is why we didn't see her in anything else? It would have been hard to pull off the Durbar with short hair! I also thought that while she could wear the Lover's Knot well, it never looked as good on her as the Spencer because of the hairdo and the tiara height. She looked good, but for comparision, the Spencer suited her much better. Now, she would have looked fantastic in that Papryrus tiara of Princess Margaret's, or the Greek Key tiara of Princess Anne's--because they follow the same general style of the Spencer tiara. But, all the others had too much going on to really suit her.
BTW, I prefered the Princess with the longer hair--