My gut feeling is that this will be a really good place for me to learn Mandarin. Fukuoka and Kobe in Japan are notoriously western cities, and both of those places are more comfortable to me than Tokyo and Shizuoka, or more pure-Japanese cities. So I'm guessing the same will be true of Shanghai.
Although I haven't studied any new material since my last journal entry, I've been reviewing everything with anki, listening to podcasts, and speaking with skype language partners about 2 times per week. On this massive, 3 country vacation I'm taking, it will be interesting to see if I retained my Mandarin as well as I retained my Japanese. Unfortunately, there was a 5 month lag between the end of my trip to China last year and the beginning of using podcasts/language partners. Also, my Mandarin is much weaker than my Japanese, which may play a role in this type of retention. I feel everything has pretty much come back, but I could be wrong. We shall wait and see.