Your time is too tight. First, when you land at Xi’an airport, you need about 30 minutes to get off and to get your luggage. And when you leave, you need to be transferred to the airport at least 2 hours before the flight departure time. The more you visit, the less time you have at each spot. For the tour in Xi’an, you are suggested to have enough time to feel its culture and history. Terracotta warriors and big wild goose pagoda may be enough.