The Marriott Riverwalk suggests the following transportation options from the San Antonio Airport

Located outside baggage claim:

SA TRAN -- shuttle makes stops at the downtown hotels
quoted $14.00 one way $24.00 Roundtrip

Local CABS-- up to 4 per cab $20.00 one way

Conference Transportation Notes:
NCSSSMST will have school buses to transport registered conference participants to scheduled events beginning with Thursday workshops including the opening welcome reception at the Institute of Texan Cultures. Friday and Saturday bus transportation will be provided based on the conference schedule.
Please refer to your conference progam and registrations signs indicating the bus stops at the Marriott Riverwalk and the UTSA Downtown campus. Any specific questions about conference transportation please contact Peggy Greff at John Jay Academy by email: margaretgreff@nisd.net