Actually, I don't suggest you stay at the airport since you have to leave the airport around 06:00 the next morning so that you could arrive at the museum around 08:00, but it is difficult to hire a taxi at the airport at that time. So, the best method is that you take the airport shuttle Line 1 to the Bell Tower where you will find several hotels, such as the Bell Tower and the Melody Hotel. Then, you could hire a taxi easily to drive you to the terra cotta warriors and horses at 07:00 in the morning. You will arrive there around 08:00 and have a 2-hour's visit at the museum. Then, you could return to the airport around 12:00. The taxi fare for a half day should be no less than 500RMB~