Avoid Chengdu, too big and polluted. But the main reason for doing so is that there are too many foreigners there, giving the upper hand to Chinese employers in salary negotiations; much better in Luzhou or Hejiang or out in the sticks somwhere else in Sichuan - the cost of living is much lower there, as are the teaching standards you'd be expected to meet not to be fired. Besides, replacements are much harder to find for employers in the small cities and towns. I can't understand why so many foreigners head for the big Chinese cities with their rat race characteristics, they'll never learn.