Layout ideas wanted

[The Black Hat]

Coming late to the party here but a few suggestions. 

Have a marshalling yard or carriage siding area near a station on one of the side runs of the layout to act like a scenic fiddle yard. 

Other ideas of scenery.

Passing loops. An area of 4 track where you just pass something in the loop. 
Quarry loading area - see Mountsorrel. 
Have a third line on one or two sides that reconnects. A branch that runs at different gradients. 
No extra trackwork. Add buildings, river, etc to change the perspective of whats running. 

Hope they are of use, but a lot will depend on the period your wanting to run.