If it's not too west for you there's Evergreen Shanghai on 38th between 5th and Madison. It's rather authentic Shangainese cuisine, also with the typical tso-tso American options. It was recommended to me by a girl from Jiangsu province.
I guess if you're there you may as well travel the extra little bit over to Szechuan Gourmet for some of the best stuff in Manhattan, unless you can't do the "spicy."
I don't mind the Chinatown Joe's Shanghai but avoid the one in midtown like a Chinese cholera outbreak. I think the soup in their soup dumplings was poo water. And it's got marked up Midtown prices.
It's been a few years since I was last there but I've had very respectable meals at Our Place II on East 55th St. The well run kitchen turns out good versions of Szechuan and mainstream Chinese fare.
Restaurant website - http://ourplace-teagarden.com/
If your group is a little more adventurous I can recommend Grand Sichuan International at 1049 2dn Ave. (55th St.) I was there about 6 months ago and thought it was quite good.
141 E 55th St, New York, NY 10022