I'm choosing a TVS diode for ESD protection in my USB circuit. I'm noticing that the datasheets for a lot of parts recommend grounding the TVS diode to the chassis, not the signal ground. I don't anticipate ever having a metallic chassis for my device, so is signal ground good enough?
Also, I'm gathering that reverse standoff voltage and capacitance are the most important qualities (for high-frequency signals, at least) to look for in a TVS diode. Are there any other qualities I should take into account? For example, I see the power rating on TVS diodes, but how do I choose an appropriate value for power? Aren't ESD events erratic and unpredictable? How would I know how much power to design for?