In addition to associating GPS metadata with photos, you can set a "home" point for photos and use the{distance}, {bearingfrom} and {bearingto} variables to sort or label your photos by distance and bearing.
Setting a GPS 'Home Location'
Set your GPS home location by navigating to Edit>Settings>Set GPS Home... Choose a location. You can use a selected photo, a manually entered GPS coordinate, or the Google Map. You can enter points of interest, or full street addresses and then use Get GPS to look up the location and plot it on the map. To fine-tune the location you can pan the map around and the marker will center itself at the new location, or you can pick up the marker with your mouse and drop it at the desired location. Use the Accept button to copy the location into the GPS coordinates section of the dialog. Use OK to finalize your choice.
Once you have set a GPS home location, you can create a custom sort to sort your photos by their distance from your GPS home location. Override one of the ten custom sorts to {distance} and your photos in the contact sheet will be sorted by GPS distance. You could also add distance or bearing information to the thumbnail previews in your contact sheet.
NOTE: As of August 20, 2023, the WebKit version provided by MacOS 10.14 Mojave is no longer capable of displaying the Google Maps views required for this feature. Users who rely on this feature should update to MacOS 10.15 Catalina or later. Photo Mechanic 5 users will need to upgrade to Photo Mechanic 6 or Photo Mechanic Plus.