Long Layover Haikou Airport

We are 4 older Australians with a long layover in Haikou. Arrive 2.30 pm and net flight is 1.30 am. We do have a Chinese Visa. Is it advisable to tax to the city and have a look around, and possible a meal. Or are the hotels that we can book a room and perhaps shower and rest? Your advice would be greatly appreciated. Cheers Heather Carey