I simply love Shuangjing, and have in office in the hotel in question (literally in the hotel), so I know it extremely well.

Back when I could reliably score it for y700++ per night (including lounge), I also thought it was a great value. But, now that their ADR is quite high, I no longer offer this assessment.

The same goes for NE too a certain extent. I used to be extremely cheap, but this is no longer the case (i.e. the word has spread).

I always stay at the YoYo (awesome value, and in the heart of SLT) when I'm in Beijing these days so I'm no longer up to date on Marriott pricing. That having been said, if you can score any of the properties I mentioned in my previous post for less than 800, you're in good shape... and, I would not pay more than 650 for the City Wall.