I like this website for PV info. This is a link to a specific article, but it tends to have current local news and events too.
Mexico: One Journalist’s View
The US governments site for travel warnings, etc.
Mexico
The US consulate in PV
Vallarta Consular Agency - U.S. Consulate General Guadalajara, Mexico
IMO: The best advice is to tell people to use common sense. Don't talk to strangers, don't flaunt your money, don't go anywhere that looks sketchy. Same thing they would do if they were visitng NYC or San Fran or Dallas or New Orleans or Toronto or Paris or Lodon....