Seeing Santorini was one of the things that when we found out we were for sure going to Europe got me to create a Europe bucket list. I don't know what specifically I heard, saw, or read, but I had an image in my head of Santorini and if I was getting so close, I wanted to see Santorini for myself. Now that I have done so, I'm truly grateful for this opportunity, and I have learned that I prefer Mykonos, because to me, it better represents the image I had in my head of Santorini.
The island of Santorini was created (they think) by a giant volcanic eruption a few hundred years ago, which demolished half the round island, leaving Santorini, and the outline of the island looks like a parentheses mark. The landscape of the island is some cliffs on the outside leading to the ocean with rather dry, desolate landscape inside. If you have seen the Grand Canyon or the Na Pali coast, in my opinion, both of those are more impressive than the Santorini coast.
Really, what Santorini has going for it is the architecture: white-washed cube shaped homes with lots of blue domed churches, all built alongside the upper portion of the cliffs. There are two main cities: Fira (the capital) and Oia (pronounced Ee-a) which is smaller and less commercialized. Fira is what most people go to. Compare for yourself and see what you think is prettier:
When we were at Oia, I stopped in briefly at one of the blue-domed, Greek Orthodox churches:
All in all, since Santorini survives on tourism now (the island ws nearly destroyed by an earthquake in 1950), if you go, I recommend staying or at least visiting Oia.