Back from Sedona Arizona on a family vacation. My belief remains undimmed–Central Park in the epicenter of Mahanttan, NY IS a vortex site as well.
Past readers of my blog may or may not recall the postings since 2007 re Central Park vortex site. (refer to archival postings search). I also did a short (10min) documentary filmed by Matt Anderson and Seth Hodes http://sethhodes.net/vortex.html you might find of interest.
Like beauty, a vortex site is in the eyes of the beholder. There are no "objective" measurements, no official vortex site registries. It is a place which attracts energy which is another vague term open to a variety of interpretations.
There is usually a rotational element to most vortices although not always easily demonstrated when it comes to other vortex sites around the world. Besides Sedona one will often find mention of Stonehenge, England, Machu Pichu in Peru, Giza pyramid in Egypt and a variety of others.
A rather new "twist" (sorry) to the concept was offered by a guide on this recent Sedona trip. A vortex site is spiritually "neutral". It does not automatically enlighten any individual. What it does is to magnify and concentrate whatever emotional/spiritual state they are in.
Those seeking to elevate themselves spiritually will find a vortes can help on this path by offering glimpses or epiphanies towards the way forward.
On the other hand, those struggling with sadness, anger, depression–ie the dark side–might find those qualities exacerbated as well.