We are about 2.5 hours from Chicago so I expect a few days travel (Mapquest says 1551 miles and 26 hours of drive time, although sometimes it estimates on the high side)  If we do 3 8-10 hour driving stints and camp on the way, it should be an enjoyable trip.  I have found (on the internet) it is best to reserve sites at the actual park well in advance of the planned date - so the wife and I have to decide which days we actually want to spend there.  We may take two weeks (to have 3 days down and 3 days back with a cushion) and spend a week or so at the campground.  

My wife has seen the Canyon before, but I never have and from what she tells me, the pictures never do it justice.  She is looking forward to going again.