There is virtually no benefits in Regent hotel. But Regent is much nicer compare with the CP. The CP is OLDDD....And there is rumor earlier this year saying the CP will be deflaged. If you have enough points, go to Regent.

On another hand, the HIX Dongzhimen is one of the nicest Holiday Inn Express in Beijing. If you don't mind using transit or taxi, Crowne Plaza Sun Palace and Crowne Plaza Beijing Airport both are very nice hotel to stay in.