The Grand Canyon is much more than a "hole in the ground" as a previous poster indicated. There are Ranger programs at the South Rim, hiking trails into the canyon, and if you book now, you probably could get on a mule trip into the canyon, That is a life experience like no other. With the kids, I would skip Vegas. They will not be allowed into any of the Casinos, many of the shows are a little off color for kids, and the in your face crime element can be daunting. Hoover Dam is OK if you like to tour factories and the like. I suggest you research the National Park's website, www.nps.gov, to study the parks along the way.