What is the best transportation to get from the doubletree by Hilton in Beijing to the PEK?

Hi Rose. Take a taxi from the hotel to Guang'anmen, which is one of the stop of shuttle bus line 7, and do ask the driver to drop you off right at the boarding site. You will reach within 6-8min and the fare is no more than CNY15. Then take the shuttle bus to the airport directly in an hour or so with CNY24.