Seems worth a try. I'd try GRMS instead (it's just $80 for the family license for 5 yrs I think). Keep in mind many FRS/GRMS radios tend to use rechargeable batteries which self-discharge pretty quickly.

However, the fact your wife works so closely is another aspect that should be planned. If something threatens you, it probably will be a threat to her. The upside is you are close. You should probably talk about pre-arranged meeting points based on different events.

For example, if something is localized and near your building, you take your son to her building. If something happens near her building, she meets you at your building. If something more widespread happens, you both go in <mumble> direction and meet at <mumble>. Coordinating those meeting points with your son's daycare evacuation plans might make sense.

+1 on at least a small light on your person. Interiors of buildings can be very dark as can subways, etc. I walked down 30 stories of a high rise a number of years back during an evacuation, and not sure what was up with the emergency lighting, but it was totally pitch black.

+1 on the consideration of shelter in place. If something bad has happened but your location is not in immediate danger, consider the potential you might be better off where you are.

The big thing I'd want improved is the PA announcement to evacuate. I would really try to get them to give a better description of their understanding of their threat. Something like "there is a report of an explosion up the street, we have no more details" is infinitely better than "evacuate the building now".

-john