Taxi from xian airport late at night.

Yes, shuttle bus line 1 (Xiaoshaomen Line) will still be in service then. By that, just get off at the terminal station - Xishaomen Airport Hotel for CNY25 per person. Then take a taxi to your hotel at a cost of CNY20 in 10min. Cab will also be available upon your arrival and the charge may be CNY130-150.