Stephen, here's a version with the center aisle cut out and duck-under location marked. 
As for the design itself, I can't find fault given your stated goals. Obviously, trains can't reverse direction, but that's often the case in small spaces. If that's an issue, you can add some reversing loops using more of the center and then add hatches for access, but that may require tighter curves than you want to use.
You can run trains in both directions, reconfigure consists using the yard, etc., so there's plenty to do depending on how you plan to operate. The one thing I do see is the siding on the right side in this image. Trains going clockwise coming out of the yard will not be able to service it easily, so it will take a train going counterclockwise to drop off and pick up.
As John pointed out, it is hard to see a "theme". As it is, there are just 2 spurs and a town to go through. That doesn't bother guys like me because I just like to watch my trains run vs "operate" them in a prototypical manner with a bunch of switching, etc.
