Looking at your layout drawing... you have one continuous loop with only one place where trains could be reversed. Isolate the middle track located at the 'car lot' at both rails at both ends where the tracks join a turnout and use a PSX-AR auto-reverser to power those rails. Good practice says use plenty of rail feeders elsewhere every 6 feet or so along every track. If HO or N scale Set up a single booster near the 'Elk Lodge' and run the twisted pair DCC power bus out in both directions to feed the layout. S or O scale may need larger amps or more boosters. Be sure to provide for powered frogs on your turnouts as you lay track.
If you plan on running with multiple operators - Consider breaking up the layout into several power districts of operation work areas. Isolating mainline tracks, yards, terminals other industrial switching track areas from each other come to mind. Each area would need a circuit breaker (either electronic or 'light bulb' type) to prevent possible interference between operator foul-ups. This would certainly complicate the single DCC distribution bus idea and may add a lot of cost. Locating individual PSX's near where they would be used simplifies DCC bus wiring.
If you plan on ever adding signaling - Break up the mainline run into practical signal blocks by adding isolating gaps. Each block could (later) be occupancy detected using NCE BD20 detectors or equivalent. For starters each block could simply be connected to the DCC supply bus.
If more crossovers are contemplated that form another reversing track, like at the SF yard to the mainline, isolate the return loops at each end and turn them into separate auto-reverse sections with the rest of the layout wired in fixed polarity.