Running them in non-multiplex mode (as you are planning) ensures that the cathode (digit) currents are low and steady, if multiplexing a 4 digit display you would run the cathodes at 4 times the current for 1/4 of the time to achieve the same average current spec.
Don't forget the Anode or Cathode resistors, even for a moment. Run the displays as close to the specified minimum current as possible, this will increase their lifespan and still be plenty bright enough. Note the recommendation in the datasheet about using individual cathode resistors rather than anode resistors if you are using the (much lower current) decimal point.
Running at higher supply voltage with higher value current limiting resistors is best, at least initially. Old displays might have trouble lighting (at all or evenly) at the minimum 170V spec. Higher supply voltage (within spec) and correspondingly higher resistor values makes it easier to control the cathode currents too (easing the demand on supply voltage regulation). At the minimum 170V spec, regulation and resistor value become critical, with a small change causing a large change in cathode current.
The MOST important rule is not to leave a single cathode illuminated for extended periods. This can cause poisoning of the non-illuminated cathodes, eventually causing uneven illumination and dark spots when they are turned on. This is more of a problem at high cathode currents but always cycle the digits.