In the spirit -- again -- of documenting in this thread the planning and preparation for the planned October 3 day hike (and an actual trip report later will be posted in the "Trip Reports" section) . . .
This last week I called the El Tovar Lodge on the South Rim to make 8:30 PM October 3 dinner reservations. (Estimated completion of rim to rim at NLT 7:30 PM.) The El Tovar Lodge is the Grand Canyon version of Yosemite's Ahwahnee, and reservations well in advance for dining there are advised. (Whether that is REALLY so or not I'm not sure, but it didn't hurt to take that advice at face value.)
Sooooo . . . if your restaurant meals are important when you do the rim to rim, just another possible tip for you. (I told the gal on the phone that I would be completing a rim to rim just prior to my planned dining time and that my 8:30 PM request was my best estimate. I told her that if after 15 minutes past that time I still had not shown up, nor had called to alert of a delay, that I was likely way longer in my hike than I'd estimated -- and to go ahead and cancel my reservation if other diners were slamming the place and they couldn't hold it.)
Otherwise, at this point only 3 1/2 weeks away from the trip . . . all remaining "to do's" are on my calendar to do at the appropriate time (and I'll note them here when they come up.)
Physical training as described elsewhere earlier in the thread has been going along nicely (and strenuously). 22 mile hikes, up and down my condo stairs 150 times, 3 mile runs all with the 20 pound backpack on me now. Taint' necessarily "fun", but as it is said, there is no gain without pain. I'm sure -- just like when I'd day hiked the Whitney main trail -- that NOT going through this regimen would make the upcoming hike much less enjoyable, if not actually jeopardizing it's hoped for success.