Mark:
I love your idea of "continuing" the line via dummy track. That is a way to "suggest" that the track connects to the remainder of the world. That is a very good idea.
Lights...they make all kinds these days. I would go with the track lighting because if you use the kind that inserts into the track you may easily readjust position.
I want to try a "new" LED that dims. All of my can lights are non-LED. I understand the LEDs can be brighter as well as dimmer and last longer. I understand that these are expensive, but I want to see.
If you do go with the track lighting consider putting each track (set) of lights (usually 3 to 4) on a SEPARATE DIMMER SWITCH. It will be very convenient to regulate the intensity of your lighting in different areas. In your application. I'm thinking 3 separate tracks of 3 to 4 fixtures each, all independently controlled, would serve you very well. I would also position a fixture directly over both turntables to eliminate shadows. Those will be a lot of photos.
Painting a town, or getting a photo realistic backdrop of either of these towns made in the background would be awesome! It would conserve a ton of space.
Lastly, I was just notified that my proof of the design book is at the printer. If Connie and I like it we will order the first run. This is an exciting time for both of us. :-)