if you can decide, move to SH. it will be the time of your life (i just came back to europe after working and studying in china for 2 years)
whoever says there is no alternative or real party scene, hasnt been there yet - shits on another level compared to the western world and the lifestyle is just completely different
i can imagine that i might be a little hard at times to be black in china, some people were really weird with me already (white and 6'7") and taking pictures and dropping racist comments in chinese and stuff, but thats normal i guess - they just dont know how to deal with different-looking people
from what i saw (yeah im white) its probably even harder for black people. many black people that go to china and live there are from african countries (mainly nigeria) that lead small trading business there, some deal with drugs, etc. and overall just have a horrible reputation. to make life for you easier you might want to dissociate yourself from these people by the way you dress or in any other way as it will be an obstacle in your daily life
as much as it might suck to stick out of the crowd it is also a benefit cause this will help you to get in pretty much all clubs, get the best girls, drink for free mostly, get involved with important people, not get in trouble with the police etc.
and the wealth thing someone described above (from my experience) is really only true for asian guys, but chinese girls can be real big bitches and turn your life into hell if they want to
the expat community in asian countries and especially china is really strong and networking and building opportunities for your future career will be real easy.
all i can say is, if you have the chance: go there but make sure to not get stuck there like many do and return to the US in time
the experience you will gain there (in all aspects, not just studying) is a big asset and if you aim to work on an international basis in the future (business, intl relations, finance, etc.) the daily life there will teach you things no college in the western world could ever do
its not gonna be easy and the first few months are gonna be extra tough, but im pretty sure you will not regret it