JF:
I think your designs look pretty good. They’re nice and uncrowded, too, with broad curves. Big mainline equipment and long trains would look quite nice, and that lets you use the heaviest N-scale equipment, which should benefit your operations.
I like this one the best:
http://i198.photobucket.com/albums/aa28/filmsomething/layout3.jpg
You might want to connect the short yard runaround and passing siding at the lower right corner, so you can combine their functions, and then turn the yard ladder 180 degrees, so the tracks branch from the middle of the runaround and then fan out to the right, not the left. This way, you can meet and run around longer trains, and also allow the yard engine to work without blocking the main.
It might also be desirable to bring the short branchline on the left side off the foreground track.
That would eliminate nearly all switches from the back, so you could push the table up against
the wall, or into a corner, and have a popout or two for the few times you need to rerail stuff.
I’d stick with the 4 x 8 and no grades for now. Personal experience tells me that somebody with a desire to model railroad but not a whole lot of time is very likely to get bogged down if he tries to get too elaborate right at the start. A 4 x 8 island is easy to build and gives a long (infinite) run for a relatively small benchwork investment. People are always saying “around the walls, around the walls”, any more, but all the same the majority of model railroads I see outside of magazines are islands.
I suspect a lot of the advantage is psychological. I can only work for a short while here and there, and with a table’s built-in limits, I can see how close I am to getting something working. I get overwhelmed when I try to build round-the-wall stuff.
If you get to dislike it later, you can always saw it in quarters and make an O or U out of it, or you could just build the table in bolted sections
