Some thoughts I had put together on layout planning. These are a repost from The Railwire.
From The Railwire – http://www.therailwire.net/forum/index.php?topic=31782.msg354453
When getting started with layout planning, a good question to ask yourself is what is your interest in trains.
Is it in operation (ie, modeling the transportation system) or is it in railfanning (modeling the aesthetics)? Are you willing to focus on one to the exclusion of the other?
If you’re focus on railfanning and aesthetics, it allows you more freedom because you don’t have to worry as much about things like having the right track plan, enough and balanced industries, balancing staging, having enough cars, etc…
You can, essentially, just have a track surrounded by the scenery you find interesting.
I’ve gone that route myself, and it’s quite rewarding because you don’t have to compromise aesthetics as much in exchange for operational considerations (in your case, this means that all the tracks in Union Station don’t have to work).
If it’s the other way, well, that’s going to be a much bigger challenge, because what you’re modeling is a small vignette of a much larger system, and doesn’t have much of the infrastructure that that system needs to support itself (for example, Union station won’t operate very well without the coach yards and engine facility, which you’d need to account for).
I’m also working on a layout following this approach, and it involves much more engineering work ahead of construction.