Try snapping to center of geometry, much less a circle in either Sketchup or Layout is time consuming and annoying.
Like a way, as in other apps, to define snap types to filter and improve performance.
Annoyance, you select edge of a circle. It show you the center. But then, like a mirage, it disappears.
But then, if you get close to the (disappeared) center, a snap point appears!
Not well enough, disappointingly.
I spend 30 second trying to find one. See I may have multiple sphere, circle, rods, among __gons in the area.
Paraphrase Steve Jobs, how many lives are being lost waiting for it to find the center of a circle.