Once you have a working drive base, figure out who wants to be driver. Give them 2 minutes of practice on the robot each, to be fair.
Now, get someone who is skilled with a remote control car (and does not want to be driver). Have them drive the car around a large area, and have the drivers follow it with the real robot. It's a good test of reaction times, handling the robot's speed, and (if it's tall) how to react to a tipping robot
Hope that helps!