I did take a room on the executive level (13th floor) at the GWS.

The room itself (1305) was a nice-enough American-sized king room with a marble bathroom. The view may have been spectacular but the thick PEK smog kept me from being able to see across Third Ring Road, much less beyond.

The buffet breakfast in the lounge was nice but at my rate the buffet breakfast in the lobby was also included and far more choices were available down there.

The executive lounge is advertised as being 24 hours, but when we showed up at 4am to get some coffee for a VERY early start one morning the attendant was soundly asleep at on of the tables and so we decided to take Stimpy's advice and use the french press in the room rather than wake the staffer.

The subway was not walkable (to my mind) but as everyone suggested taxis were plentiful and cheap.

All in all it was a solid experience and I'd recommend it.