So very true that each visit brings a new sense of the "Grand" Canyon. Have been able to visit the South and North visitor centers and views are mesmerizing!
BUT I keep going back to Tuweep (Toroweap), a very narrow portion of the canyon with great access to shear walls and veiws down the river both east and west. Both sunrise and sunset grandeur. Even the campground (aprox. one mile from the overlook) is a great site, IMHO. (dry camping-no water, pit toilets, 60miles dirt road, 9 sites + one group site)
Not sure about winter access due to road contions etc. Later April/early May was green with lots of flowers starting to bloom!
Hope to get back this year!