If you like more desolate drives, come down through Nevada :)
Cedar Breaks Nat'l Monument is in the Dixie Nat'l Forest area. It's like a mini Bryce.
agesilaus described Hwy 89A, which goes from Kanab to Jacob Lake then to Bitter Springs. The more direct route from Kanab to Page/Lake Powell is Hwy 89. And along there is the Toadstools hike (short hike to some cool rock formations) and an interesting dinosaur exhibit at the BLM Big Water Visitors Center.
Top things to do in Page/Lake Powell...Antelope Slot Canyon, smooth water float trip below dam on the Colorado river, walk out to Horseshoe Bend overlook.
If you stay in Flagstaff/Williams, you might want to take a day to drive down through Oak Creek Canyon to Sedona. I think the best way to experience the Grand Canyon is to stay the night in a South Rim campground. More chance to see elk and deer roaming, and sunrise/sunset create beautiful lighting on the canyon walls.
I agree, there is alot to see and do in these parts. You'll have to pick and choose a selection of them to fit into two weeks.