Central America travel advisories and vaccinations

I bought my plane tickets.  Now, the real planning begins...

Guatemala
Visa: None for Americans staying for 90 days or less.
Threats to Safety: Large demonstrations, drug and human traffickers, locals who mistake foreigners for child kidnappers, armed robberies, carjackings, kidnappings by indigenous activists, general kidnappings, many criminals use police uniforms and cars, poorly maintained vehicles, drunk driving.  Between January and September 2012, an average of 95 murders per week in the country.  Since 2008, 31 Americans have been murdered.
Vaccinations: Hepatitis A, Hepatitis B, Typhoid, Rabies, Malaria

Honduras
Visa: None for Americans, but proof of onward travel is required.
Threats to Safety: Political demonstrations (tear gas, water cannon, rubber bullets), land mines along Honduras-Nicaragua border, flooding, Peace Corps suspended program in 2012 due to safety concerns, highest per capita murder rate in the world (86 per 100,000), kidnappings, armed robberies, carjackings, pirates.  Since 1995, 108 Americans have been murdered; 29 cases have been resolved.
Vaccinations:  Hepatitis A, Hepatitis B, Typhoid, Rabies, Malaria

El Salvador
Visa: No visa for Americans staying for 30 days or less.
Threats to Safety: Political demonstrations, strong currents/undertows, extortion, shootouts, carjackings, armed robberies.  70 murders per 100,000 residents.  13 Americans killed since 2010.
Vaccinations:  Hepatitis A, Hepatitis B, Typhoid, Rabies, Malaria


Nicaragua
Visa: No visa for Americans staying for 90 days or less.
Threats to Safety: Political demonstrations, domestic air travel, violence-robbery-assault-stabbings near Ticabus terminal (shit).
Vaccinations:  Hepatitis A, Hepatitis B, Typhoid, Rabies, Malaria


Costa Rica
Visa: No visa for Americans staying for 90 days or less.
Threats to Safety: Not too bad, relatively speaking.
Vaccinations:  Hepatitis A, Hepatitis B, Typhoid, Malaria


Panama
Visa: No visa for Americans staying for 180 days or less.
Threats to Safety: Avoid remote areas of the Darien Province (first sentence of advisory), FARC, ELN, AUC, drug traffickers, general crime at around Costa Rica levels.
Vaccinations:  Hepatitis A, Hepatitis B, Typhoid, Yellow Fever, Malaria


Source: U.S. State Department and CDC