It sounds like you truly appreciated the majesty of the Grand Canyon. I had the privilege of being an Artist-in-Residence at Grand Canyon National Park. It is a place that is very special to me, which is why I moved to northern Arizona as soon as I could. It's great to hear that you have been touched by this place.
You learned a lot about what you need and don't need during your quick visit to the canyon. I'd like to add that if you do a helicopter flight, I suggest flying from the Grand Canyon National Park Airport in the village of Tusayan. There are two different flight that can be booked, and I suggest the longer of the two. It will give you the best aerial views of the canyon including a view of the confluence of the Little Colorado River and the (big) Colorado River.
A few tips for your helicopter flight. Do not allow your camera to come into contact with any part of the helicopter as this will transfer vibrations to the camera potentially resulting in a blurry photo. Also, wear dark clothing to minimize reflections on the window. Don't worry too much about depth-of-field when photographing from the helicopter. Put your camera in Aperture Priority and stopped-down 1-stop from your lenses fastest aperture. This will result in the lens performing at it's peak performance with regards to sharpness and will also keep your shutter speed fast.
I see that you are planning to visit the canyon again in May 2014. If you can, I suggest postponing your trip until the monsoon season which runs from mid-July to mid-September. This is when we get our thunderstorms with lightning and rainbows. It's a truly stunning season. I hope you don't mind, but I'll share a photo of what can be experienced during the monsoon season...
Date: August 2012
Camera: Canon 5D Mark III
Lens: 16-35mm f/2.8L II
Exposure: ISO 160, 30 seconds at f/9
Filters: Singh-Ray 2-stop soft-step graduated neutral density
Notes: new shorts needed after the shoot.