Hi Mark,
I'm so glad that you have made up your mind to teach English in China. Before you make a decision about your precise destination, let me introduce my hometown, Chongqing.
Located in southwest China, Chongqing may not enjoy worldwide fame as much as Beijing or Shanghai, but it is a thriving metropolis with lower cost of living. Working and living here, you can achieve your career goals without feeling too much stress. The locals are known for being warm and hospitable, and you can teach in a way that feels good for you. To be sure, teaching a foreign language in a city where residents speak a dialect all the time can be very challenging. It takes time indeed to correct pronunciation mistakes each student makes. But since you are always praised for your kindness and patience, it should hardly be an obstacle for you.
Anyway, I will support and help you as much as possible, whichever city you go to. I believe living and teaching in China will be a pleasant and memorable experience for you.
Best wishes,
Li Ming