I'm from the Bay Area- hopefully my answer will a little more enlighning- I moved to Lake Chapala area 3 .5 years ago - 90% of the Expat community is over the age of 60- I found the life in and around the villages REALLY NOT like liviing on the pennisula, Marin or East Bay. Villages are very collquial -small town attitudes, and ideas----marrieds only mix with marrieds and singles have to find a group. People rarely go out at night- life dies after 8pm
My house was burglarized twice--- the crime wave you read about exists- I lived in the Bay Area most of my life and never experienced the crimes that exits in and around Chapala. Car windows broken- antennas broken off - spare tires ripped off a jeep etc-you must be vigilant 24 hrs a day in your own home and live with doors and windows locked.
Finally, I had it and luckily sold my house and moved to Guad- Zapopan 9 mos. ago- What a DIFFERENCE - a real city- with nightlife- restaurants etc-theatres etc but laid out like the suburbs- very similar to LA
City is spread out- so you really can live in the City and be anyplace in 15 minutes as there is no real city center of restaurants bars, movies malls etc-
Zapopan is the newest part of the city - Univ of Guad is located here as well as other universites , Shopping malls etc. and I would suggest that perhaps you might want to look there first or close to the city line for a place to live if you decide to come here. The city is made of small gated apt complexes, housing complexes etc, but it is so normal - you don't even think twice about it

However, Mexicans in Guadalajara are a very closed society- they socialize with family first, then friends they have known since school- or people they work with- IT IS EXTREMELY DIFFICULT TO BREAK INTO THESE GROUPS- UNLESS YOU KNOW SOMEONE MEXICAN- this is not just my opinion- but the opinion of Mexicans themselves-who say- Why do I need anybody Else ??

I was fortunate- as I had been in business here- so I have an IN- but even with that- it is difficult- depending on your level of Spanish. Most all Business people speak English- BUT- of course they prefer to socialize in Spanish- you will always be at the bottom of their list for for any kind of get together- lunch, diner, going out etc after family, old freinds etc Something to really think about-
I know younger people who came here from the Bay Area and could NOT make it in Guad's very closed society and Left disapointed.

Hope this gives you a better picture-

PS Air Quality is only usually bad in March, April- May- hottest months