Anyone ever backpacked in the Grand Canyon?

[Tri Girl]

Ok, so next summer DH and I are planning a 4-5 day hiking trip in the Grand Canyon. We are planning it for just the two of us- not with a group (we like to do our own thing- and group tours are crazy expensive). I'm SO excited (and it's still soooo far away). I know summer is the worst time to hike the canyon, but seeing how I teach, and that's the only time I can do it- it will have to do.
We went to the Canyon last summer and hiked 3 miles down and I knew I had to go back to see more of the canyon. It's beauty is amazing/scary/intimidating.
I've already bought him an internal frame backpack, and am keeping my eye out for one for me. We've climbed a few 13,000+ ft mountains, so the logistics of hiking/backcountry camping aren't new or scary to us, although I know that canyoneering and mountaineering are VERY different birds.

I've been scouring the internet for training programs, but have only found mountaineering programs to use (a training program for climbing Denali will work for conditioning/strengthing). I've purchased numerous books about hiking the Canyon and am reading them all the time.
We'll be carrying lightweight camping gear (tent/sleeping pads/sheet), water purification system, dromedary, stove, etc.

I'm just wondering if anyone has done it, and what your experiences were like. I'm nervous about getting a backcountry permit (need to apply 4 months in advance), but hoping we'll be approved. That will determine if we get to do it or not.

Any tips, advice, etc are warmly welcomed!