Code 55 track also looks very good. I have found pre-weathered track to be both easier to use and better looking than weathering it myself. Just use a fiberglass brush from Radio Shack to clean the rail before soldering. If you solder flex-track while straight before bending it into curves, it helps avoid the kinks at joints. Track is held directly to the masonite board by the matte medium or glue holding ballast in place.
All track is as flat and level as possible to make switching easier and eliminate derailments.
Sidings are mostly straight to facilitate coupling and uncoupling. It is darker blue at the top, fading to light blue at the bottom, with perhaps some distant looking mountainous shapes. Nothing fancy, just something to convey depth. A wood trestle on a modern railroad is a bit out of place, but I had to have just one. My next modern layout will probably use a steel one or a stone viaduct, as they withstand the weight of modern trains better, and don't burn as easily as the creosote coated wood ones.