Transit in Guangzhou less than 24hr

We are flying from Thailand to Los Angeles with a Stop in CAN. Our stop is 23 hours and we would like to go out of the airport to visit the city. Our passport is from Mexico and my question here is should we apply for the 24hr direct transit or for the 72-hour visa-free transit.
Do we need to apply prior our arrival or on the airport?

Thank you in advance.