Ever since I was a kid I would have to say Niagara Falls both on the Canadian side and the American side. Whether you cross it on foot via a bridge, go over it in a plane, helicopter or gondola, butt up against it in a boat the falls are truly worthy of being a "wonder" to behold. And the gorge is breathtaking too.
I would have to say the Northern Lights. The first time I remember seeing them I was driving my car and the sky lit up with moving sheets of light. At first it caught me off-guard and then I realized what it was and simply watched it in amazement.
The type of poetry that intrigues me is the type you would not expect to read, something creative and out of the blue. Something odd and something that's truly deep within the possibilities of the human mind.