Dear Kyler:
Remember you asked for an opinion. :-)
I don't know where to start. First, you are BLESSED with a wealth of space that a majority of people don't have. You have the opportunity to create a truly great model of a railroad.
I understand you are not a rivet counter. Neither am I. However, I having about 45 years in this hobby have experienced enough to tell you that 95% of everyone gets tired relatively quick of watching trains circle. "All that's missing is the Christmas tree" are the words most often used to describe looping layouts. My first 20 some odd years and 6 to 7 layouts looped. I finally came to understand why I was so bored. I wasn't doing anything, the trains were chasing their tails and my layout was "railroad USA" not supposed to be representing anything particularly, but giving a non-nonsensical presentation.
First, you must decide if you are building a: toy train layout, a display layout or a model of a railroad. If its a toy or display layout go ahead and circle away. These types of layouts serve no purpose other than to show off trains running or using the toy accessories. These are fun layouts but won't keep people's interest for very long.
It sounds to me like you are interested in building a model of a railroad; even though you wrote about allowing "two trains to run relatively unattended." I would advise you against doing that because that is exactly what I did for more than twenty years and six different layouts. I got bored quick.
I'm going to a guy's house next Saturday who has an awesome display layout filling his huge basement. He told me he rarely goes down there anymore and wants to change it. Even as big and impressive as it is, all it does is loop. The first time I ever saw his layout I immediately thought two things: First, how in the heck does he reach the center to clean? That thing is 14 feet wide! God almighty! Second, you've got that much space and all these trains can do is run a circle? Really?
Guess how many times people who have seen this layout return?
The most odd thing about your Post that really caught my attention is you have MULTIPLE ideas as to what you want your layout to be. (I'm assuming your definition of "High-Rail" is a ""REALISTIC APPEARANCE" with 3-rail track.)
When people request assistance or opinions with a new layout I ask them: What is the layout's name (What railroad(s)) is this? WHERE is it located? Why was it created? What does it to do to earn revenue? Does it still survive?
Any good layout must have three essential elements for long term success: Plausibility, Purpose and Participation. In other words, it's gotta be believable--even it completely made up, there has to be a purpose for it--is it hauling, frieght, passengers or doing something like??? And VERY MOST IMPORTANTLY, what are its Operators' doing? The answer should NOT be standing there watching it chase its tail.
What I've written will NOT be received well and I got the angry hateful comments routinely, no big deal to me, because more and more people every day are going wise to what I'm sharing with you.
In YOUR case, it's GREAT that you have all of those awesome wonderful ideas. Really. BUT, you need to narrow it down to one idea. It is far too big of a stretch to model the pacific northwest with the N&W or Pennsy. It's not logical. The scenery is entirely different even in the same era. You won't be able to make the layout plausible because that is just too big of an area. I've seen that done more times than I can tell you and most of the big plans turn into nothing but another "Plywood Pacific" dust-catcher.
If you want to do an east and west railroad, I would suggest building two separate railroads on opposite ends of your basement so that one will not detract from the other.
I'm like you and most others with era, I don't stay true to one. My layout is modeled after the real rail line that runs through Marias Pass. My layout is 2 scale miles long of non-repeating linear main line--a single line with passing sidings exactly as it is in real life. I run anything and everything that has every run in the actual pass. My Crew and I do attempt to run "like" trains together. In other words, we don't run steamers with Amtrak Superliners.
CHECK OUT MY LAYOUT PLEASE. There are several videos on Youtube. My link is below my signature line.
I would highly recommend to you, with all that space, get your trains actually going somewhere. You can do it. Specifically, plan your track arrangment like two table forks with the tines of the forks opposite of each other and the handles touching each other.
Also, arrange your track line to travel through each scene only one time, and a each "end" of your main line, have a reverse loop, wye track or turntable, so that a train can be reversed to return to it's point of origination. You would probably prefer the reverse loops on each end because that would give you a way to allow a train to run itself--you could control the other to "meet" the free running train. IT IS MUCH MORE FUN TO ACTUALLY CONTROL THE TRAINS!
Lastly, all of my prior layouts, until THE GLACIER LINE looped. I was pretty much the sole person having anything to do with the railroad. Now that I've constructed this basement point-to-point (I too have reversing loops at each "End"), I have six other regular Crew members and about 5 to 6 more current visitors who have expressed interest in operating with us every other Sunday evening. It is must more fun and enjoyable to share this hobby with a group of people, but most people get bored with circling almost immediately.
If you want to send me your basement measurements, I'll give you a sketch for a track arrangement. HOWEVER, you must tell me: what this railroad is, where it is and what its doing.
The track arrangement in New York City looks different than the Dakota Plains, West Texas prairies and Nevada desert. Do you want a yard, two yards, no yards, main line, branch line,.........is it just a coal hauler, is it a logging railroad, is it standard gauge, narrow gauge, electrified?????????
The model railroad design process is much greater than just fitting tracks to a space. I'm stunned that you weren't inundated with loops piled on top of loops for your AWESOME space.
My advice: if you want a high rail track, build a model of a railroad and NOT a roller coaster, spaghetti bowl of track. That has already been done over and over and over.............if you had a smaller space that is understandable but you've got a gold mine.