Learn how to use the new Ruler tool found in SideFX Labs. It is in beta so you need to turn off the production build option when installing or updating Labs.
The Ruler tool is an nodeless viewport state for measuring distances on geometry. With it, you can quickly get values for the rough sizes of different features on the geometry, and use the measurements to inform your decisions about parameter settings. For more precise measurements, you can turn on point snapping or grid snapping. You can also enable angle-snapping, for locking your measurement to make a specific angle with regards to the x, y, or z axis.
The measurements can be copied to the clip board for quick pasting into parameter fields. You can add as many measurements as you like, but keep in mind they are ephermeral and will disappear once you exit the viewer state.
You can access the tool through the Sidefx Labs shelf, or from the Tab menu while your mouse is over the viewport.
The tool currently only works inside a SOP network, and you must have the display flag on a node.