We go to Egypt because we have family there, and they have suffered a lot of unrest and State Department travel advisories, etc. I feel more comfortable going to Egypt than Mexico, personally, because of all the violence and targeting of Americans in Mexico. However - never say never. Research it thoroughly. A lot depends on region, modes of travel, etc. Check the State Department for travel advisories and warnings.
Kidnappings of children would be my greatest concern, personally:
"The rising number of kidnappings and disappearances throughout Mexico is of particular concern. Both local and expatriate communities have been victimized. In addition, local police have been implicated in some of these incidents. We strongly advise you to lower your profile and avoid displaying any evidence of wealth that might draw attention. "
http://travel.state.gov/travel/cis_pa_tw/tw/tw_5665.html