I love all the spines I've seen thus far! Marie, I am a huge fan of the spines created from Japanese book binding, and I'm so glad you posted it. That method has long been on my "try it out" list.
My favorite spines are those of classic books. I already have a thing for classic book covers, and I love going to Barnes and Noble and looking at them. They are just as decorative as any vase, portrait, or home accent. I didn't find a picture of them all together on the B & N site, so I was able to Google it, and up popped the picture below. I love that they are all shown together, so you can get the effect.
I wish I had them sitting on my shelves!