SN74CBTLV3257: Questions of SN74CBTLV3257PWR

Yes; data I/Os of analog switches can be left open (unless you're using very high frequencies); see [FAQ] What to do with Unused Pins & Exposed Thermal Pads?

Hi Jimmy,

For I/O pins, it depends on the application you're using. For low frequency applications, these pins may be left floating without impact on other channels or operation. For higher frequency applications, I advise that the unused I/O's are tied to GND through a termination resistor due to a possibility of noise coupling to the unused I/O's. As Clemens noted, please see [FAQ] What to do with Unused Pins & Exposed Thermal Pads? for more information on this topic. 

Thanks!

Alex