Where can i go from Changsha airport between 9.30 am and 5.30 pm?

I arrive on a weekend at airport from Haikou at 9.20 am and i have to check-in to the flight to Haikou at 5.30 pm on the same day. Where can i go from airport between these timings? Are Orange Isle and the Hunan Provincial Museum worth the visits on a weekend? How about short return flight to Dayong airport of Zhangjiajie for aircraft-spotting at 11.40 am?

Does Airport allow aircraft-spotting photography outside the terminal building?