Many times, many canyons, buttes, etc. By foot, boat, technical routes, etc.
I have done this trip 5 times going back to the late 70's and as recently as 2003 with my wife and two kids. A great companion book for the trip is John Wesley Powell's "The Exploration of the Colorado River and Its Canyons."
Canoed down this section of the river with another couple. We both had 5 month old kids that were only a day apart in age. Canoe camping with kids sure beats backpacking where you have to carry the little boogers the whole way. We did the trip in only 3 days, next time we will take at least twice as long when the kids are a little older and are ready to hike some of the fantastic side canyons.