Here is our experience, if you'd like yet another person's input. We just got back 5 days ago, from a 2 week vacation at the CasaMagna Marriott in Puerto Vallarta, Mexico and we felt completely safe the whole time. While I can't speak for the rest of the country's safety, the Marriott does everything they can to make you feel safe getting to and from, and around the resort. The Puerto Vallarta area always feels safe also. The whole town pretty much lives off tourism and the people seem to work hard at policing themselves. There are several large cruise ships that stop at the marina during the week, and some days you will see 2 ships in port. We have been going there for 3 years and, for our own feeling, wouldn't hesitate to go back. We are a little more adventurous than some might be, and take buses out to the little more remote local areas, but that should be done only at your own comfort level with some time and with a lot of research first.
PV is an excellent choice. I was there with my family last winter. PV is less of an American destination than Cancun. It is still a tourist experience, but more of an international one. PV is an old Mexican city that is fun to explore, with lots of great dining opportunities. As for safety, tryt53 is correct, but I would go even further to say the city goes a long way to assure the area remains safe. Tourism is the engine of the PV economy. The residents and businesses there need it to be safe. Keep in mind also that Mexico is a big coutnry and our media has a tendency to simplify messages in its hype (i.e. "Mexico is unsafe"). The USA has its danger zones as well, but that does not mean one should not tavel here! That said, I would stick to well travelled and generally recognized safe cities. Do not travel by car to remote destinations or long distances city to city. In other words, apply common sense guidelines and you will have a wonderful time.