I am an American and my wife is Shanghainese. We bought a place in Shanghai 7 years ago, so I have been going there every year since. Finally last year I decided to try and learn Manderin instead of relying on my wife to translating everything.
I'm disappointed to hear so many people complain about Tao. David was great for the beginning lessons, But if people want to learn Chinese, they better get used to listening to Tao. We have a lot of friends in Shanghai, and they all sound like Tao.
My advice is to practice and practice more on listening you you and Tao if they want to actually understand the Language. As I said, dave was great for the rudiments, but if all you did was listen to Dave, and went to China, you wouldn't understand anybody.
Finally, you should put a bulletin board on this site, When we are not ins Shanghai, we rent out the condo for business, and personal Travlers for short terms. This way they can have a nice apartment instead of staying in hotels. If anyone is interested, they can visit our website: jjbshanghai.webs.com