Wiring a new O scale layout for Lionel and MTH operation

Looking at your track plan. I would start by setting up the outside loop. Looks like the only switch involved is the double crossover. That will get you a train running.
As far as wiring. My layout is buss wired. Works fine with DCS but my layout was built long before it was available. I would go with the recommended paired wiring. Probably go with 2 or 3 isolated blocks on the outer main. I’m  guessing your switches are pre wired from Ross and I really have no experience in how they do it. I know on my double crossover. I soldered a wire to every isolated rail. They all can serve a purpose and some change polarity through relays to eliminate stalling. Todays engines feature more pickup rollers and axle wipers which can eliminate a lot of fancy wiring. Still even if the wires are never hooked up. They are in place if you need them.  
Once you get the outer oval up and running. You have the satisfaction of seeing a train traverse the layout. At this point. You will want to do a signal test with your DCS setup. The loop is pretty basic and should yield solid 10’s. When your satisfied with how it works. I’d focus on the turning wyes and getting that operational. I’d put the yards in last. As far as blocking the layout. The Ross turnouts originally had no wiring and had natural breaks in the center rail. If you have the Ross Ready switches. I believe everything is connected. You can still use insulating pins or just leave the center pins out to achieve your isolated blocks.

As far as piecing it all together. You can build the inner loop in place with all the switches in place. Even if one of the legs goes nowhere for a time. Gargraves has what the call fit up blades. Rather than pulling the track apart to insert pins. The track drops down over thin blades that keep  the rails in line.

You have a good track plan for building in stages. Use a good quality wire and constantly test your work running trains.

Dave, thankyou for your feedback. Great advice.

Do you have the Barry Broskowitz book on DCS?  It's a good place to start.

I will look into aquiring it. thanks

@R Packard posted:

I will look into aquiring it. thanks

There are several editions of the DCS Companion out there.  The version that covers wi-fi also covers everything else; 2nd edition is the latest.  (Looks like Amazon currently has it at a discount.) The 3rd edition is the most recent version of the non-wifi book; the first or second edition may or may not be adequate for your needs - if buying one of those, be sure to get it at a substantial discount.

Before his untimely departure, Barry told me that the WiFi Companion was the one that would be upgraded going forward, and that everything in the DCS Companion would be included.  I have both, and AFAIK, the WiFi Companion is complete as far as it goes.

Not sure who's going to write the WTIU Companion.

Thank you all, I am looking into the publications now.