If you use wire diameters (or areas) you only need to memorize the resistivity of copper which is about 17 nanoohm-metres. Resistance/length = resistivity/area.
So for 1mm diameter R/len = 1.7e-8/(pi * 0.0005^2) ~= 0.022 ohms/m
From the wire dimensions you can also calculate the weight of copper and thus the likely cost too - not so easy with wire gauges. And if you are winding coils the dimensions are useful for sizing coil fill areas/volumes too - again wire gauge isn't useful for this.