Dave, you can also Google train stations along the Philly to Harrisburg, etc. such as the R5 route. As I recall from years ago taking the R5 to Temple University from Paoli, there were 4 lines, 2 eastbound and 2 westbound, with the inner lines being local and the outside lines being express. Like you, I don't have the room for passing sidings, but I can use trickery by using my outside mainline as a passing siding.
Also, there is tremendous vestiges of the PRR still left and a wonderful array of scenes to model in the route referenced above. I think my love of urban railroading was established as a child and then reinforced as a young man taking the train into the city from various directions; tunnels galore, giant industries and smoke stacks, every square yard seemed to be utilized back in the old days.
