Thank you for your comments, John! When Dave first saw my topic, I would think he probably noticed similarities in my crude software drawing with a design he was working on for himself last year. My design was influenced by his and another fellow, Jason17112. Of course I was asking anyone for ideas as that concept was not just what I was looking for. As too S curves, yes those are details that can easily overlooked until someone else points them out. Thanks for that. Yes, the holding yard is a concept that seems attractive, but even as I tested that I could reach in an pick up cars on the front two or three tracks, but what happens if I need to repair a bad switch or section of track? I admitted above, I would have to make the top level removable, or the lower yard track slide out; both of which would probably be nightmares for me to construct and maintain in themselves. When Dave added it to the design a number of days ago, he said he was just throwing it in for comment. I am thinking the only part of it that would be practical for me would be to only have one track going off the mainline there and staying right at the front. No there isn't really any prototype for it in the real Blackwater Grade, but there is no passing siding either. I have the track diagrams for the whole line from Elkins to Cumberland, which I got from the Western Maryland Historical society back in the 1990s. The section in question only shows two stub sidings along the grade, one about 1/3 of the way up and another 2/3 of the way up. I am not interested in modeling them. No room for the flat spots for one. As I said a day or two ago, I probably wouldn't use the passing siding when operating alone, which would be most of the time. If the lower yard under the Davis/Thomas area wasn't there, the passing track could be longer, but I'm leaning against that.
You are right, I do want to have trains go from one place to another with a purpose. That is the point to point idea. However, I do like to see a train travel a ways before reaching it's destination. The clever ways both John and Dave looped track around to make a longer run really helps this problem. Still I envisioned the run being too short. That is where I drew on the thinking of layout builders who use the oval make a few laps, and stop at the station and set out a car. Then they continue along, and when they come to the same station in a few laps, they pretend it is a different town, and set off a car at the other siding, and on it goes. I admit, I have found the concept to be a bit hokey, but I can see it would work for the person who has little space, and doesn't want just a small switching shelf layout. I don't want to do it that way, but I think I would like to say make a train at the bottom, run up to the top, but loop back behind some false fronts, trees, or something that can be make it look like the train just went out of view. when it comes back into view before going down, I would be thinking in my mind it is going on down the other side of the mountain to another town. It could loop back at the lower town and go up again where it would terminate giving a run 3 times as long. Yes, I would have to use imagination, but I think it serves both desires, since I am way short on room to make a run that long linear.
As to access; I didn't ask, but I took for granted that Dave is representing a person with the blue circles, but with the larger cutout access area with the black lines farther out around them. I can make foam based lift out scenery to cover them when I don't need access. Now, the blue loop at the bottom is near the window that goes into the laundry. it is low enough, I can reach through there to access that area. I do not know yet whether I will leave it open to view the layout in that way (I think my wife wants it open), but I could make a removable backdrop section on it. If the blue yard isn't there, I could make another access hole there. I did realize that I wanted a bit more scenery than the turntables would allow.
Oh, another note, I could not envision the scenery I wanted with the long grade downhill with the downhill loops crossing over themselves. I sent Dave a couple scanned photos of an HO layout from another magazine publisher. I thought it improper to post the photos from another magazine here, though I would like to very much. This arrangement allows for that type scenery whether the passing track is in or not.
John, the very best idea is the one you suggest where I lay it all out on the floor and try it out. I have the room fairly empty; yesterday I took down the grade test and the reaching into an 7" high enclosure test. I also have a bunch of engine and rolling stock boxes in the room that I put there when I emptied the closet under the stairs to find my books and articles. I took photos of the box ends to go with my spreadsheet listing everything I own. I am ready to pull the remaining boxes out to photograph and put them all away. I have the little table with my Z4000 and DCS on it that powered the grade test. Once the boxes are out of the way, I will build the mainline with turnback loops on the floor, (Dave's plan) and try the scenario I mentioned above for a while, I will then remove the turnback loops and make it truly point to point and try it out that scenario for a while. Then I will have a better idea of what I want. Do I want the point to point I was planning many years ago, but in a much smaller space in a much larger scale, or do I want to fudge some to make the run seem a little longer. At this point, I am going to take the neutral stance and see what happens. Excellent idea John!!
In the meantime, I will buy paint, research some track lighting, and price lumber.
John and Dave, thank you both for lots of contribution, and thank you everyone else who have thrown in some other points. I will welcome anyone's comments! Who knows, maybe one of you out there has a third very different option you would like to share!! 
You are welcome to share if you do have anything. You don't need to support Dave, John, Me, or anyone. I'm pushing 61; though in time I realize I may want to make some changes, I do not want to be dissatisfied with the whole concept a few years from now but not feel like starting over.
