If you can take the emergency days off the back burner and add them to the trip, you will find it could make for a memorable trip. A couple of days with family, a couple of days at the GC and 7 - 8 days there and back. That should give time to check out things of interest along the way.

A couple of suggestions. If they have not done this in the past, make sure the children keep a daily journal of the trip. It need not be lengthy, and can (should) include what they did / see in words, drawings and photos, as well as any souvenirs such as entry tickets. There is no right or wrong way to do this, so allow them each to develop their own style. It might surprise you.

The other is, make sure, if you possibly can, to take in a sunrise and / or sunset over the canyon. It is an experience not to be missed.

Lifey