I finally put something together today than had been puzzling me for several months. There are 12 sections of track in the layout each with its own power control. I have been able to spot in the plans where each was and understand how each was supposed to be wired, except for section 8. I couldn't find it anywhere. Finally today I found a lone "8" not-near-enough to the track in that section. Section 8 does not use a terminal track piece like in other sections but a pair of terminal joiners. Therefore, it looked different in the plan, with no clear link between the digit and the place where the terminal joiners go. I had never noticed the 8 positioned as it was, kind of orphaned from its track location. But today, finally, it all came together.
I have always been nervous working with electricity; the last time I messed with something around the house involving electricity, I called my dad to get him to talk me through it. Also I recently found a discussion board that includes a lengthy thread helping someone else who built this same layout. He encountered a problem and got lots of help, all of it in the discussion. That has been very helpful. The coolest thing I've got working is the turntable. I was able to get the electric control, so I can make it spin to each of the spurs by working a switch rather than using a hand crank.
Of course the big thing in model railroading is the transition over the past few years from direct electric modelling to digital. I'm definitely in the stone age camp. But digital does open up lots of possibilities. One obvious thing that some folks have encountered is the ability to have a locomotive equipped with a camera send a feed to a video monitor, so guests can get a "track-view" perspective of the layout. I've got no illusions. On top of everything else, the new stuff is very expensive. Maybe next time.