I am focusing my efforts on the rail station scenario terrain. I have a solid idea on what to do for the passenger platforms. I picked up an HO scale passenger walkway at the local train store. It is a nice piece but fiddly. I have it mostly superglued together. What I needed was the passenger platforms that they would rest upon.
I stole the idea for the platform from Matt. He purchased some laminate tiles from Home Depot that looked reasonably like concrete. They come in 1' by 2" lengths. I cut them into 4" wide by 2' long strips. I will have to do this for two of the tiles to get the station to cross my games table. I intend on mounting these on some wood to keep them flat. Then mount them again on a long board to keep the whole thing stable. This will also give the train track bed some depth from the passenger platform.
For train tracks, I purchased a bunch of them from Mark IV Miniatures. I just got the straight lengths. I will have four sets of 4' long track sections to paint up. I just need to figure out the spacing between the passenger platforms to have room for the double track lengths.
Once this is all together, I can start to worry about the train station. I have assembled the structure that I will use but I have not painted it at all. All of this will occupy about half of a 6' by 4' table. The rest of the table will be generic urban buildings.