Landscape shooters - how to get near and far in focus. Question about DOF and diffraction

I would put it very simply.  Don't use f16 when f8 will do, but when you need f16, use f16.  The small loss in edge sharpness due to diffraction is minor campared to not having the depth of field you want for your image.

Another approach for still subjects is to shoot at several apertures and blend them either by hand in photoshop layers or in focus-stacking software.