Your wife is at work. If she doesn't work, she is at the market, or anywhere except at home. You work 35 miles from your home. The kid in high school travels by bus 9 miles to school. The other kid is five blocks from home.
The market is 2 miles from home.
Floods. ( more people are killed in the U.S. by floods than any other of natures disasters per year). Or some other man made/caused goof up.
A meeting place, a place to leave a note. Sure we think at first, cell phone. I think that may not be an option in a huge problem type of disaster. When the 9-11 hit you could not get to New York, for the most part by cell phone. What does that leave you? A CB, well they are very short range in the best of times , and they will be jammed. Right now they are jammed in or near any large city, under normal conditions. And who are getting through to? Your other half doesn't have a CB and I’ll bet you your kids do not either. A Ham radio, they might work to get you in touch with another operator, but again do each of your kids have one as well as the other half. The communication factors by radio of any kind can very limited and may fail all together.
With families I consulted with, on this important plan, it takes way longer that you might think to work out the kinks and the what ifs, they are different depending on all the locations of each family.