Based on my experiences on a 2 night stay in 2007, Westin Financial Street is in a pretty businessy area. There is not much happening there after hours. It's also a bit of a walk to the subway.
If you're doing touristy things, I'd stay closer to the Forbidden City. This way you will not be spending all your time transiting between locations. There are more tourist attractions (ie English menu restaurants) over there as well.