One of the great aspects of this hobby is that each individual can choose where on the various spectrum they want to be. You can be an extremely serious modeler of equipment and simply like to watch trains run "in circles", or a savvy student of operations bent on recreating the feel of the prototype to the fullest with un-weathered equipment spotted at cardboard boxes vaguely resembling buildings. OK, those are extreme examples and presumably the serious operator would get around to weathing the cars and building actual structures.
Personally, I fall more towards the railroad modeling end of the overall spectrum and seek to recreate the operations of the prototype. There are an infinite number of ways to achieve that, ranging from basement-sized empires recreating a many miles of territory down to smaller layouts focusing on just a few industries.
The smaller has become very appealing lately. The trend began for me with the design and construction of the Beer Line (that was published in Nov 2011 Model Railroader). Even though the Beer Line soon grew to three times the size shown in the magazine and became a representation of the entire six-mile branch line, it still feels small in the scope that it sets out to capture.
I hope to achieve the same with this Frisco spur. At less than two miles in overall length and with just a handful of industries, it feels achievable. I'm probably still a ways off from building (space acquisition), but the research has been just as much fun -- figuring out "how it used to be".
Along the way I keep coming across more and more great ideas that follow this same theme. The most recent I discovered was a series of feature-length articles by Mike Cougill of OST Publications. I recently read Vol. 5 about switching operations and it's message about studying the prototype, understanding the "why" behind its operations and using that as an input to model railroad design is a much more elegant presentation of my own thoughts. Go read it. When I get to more building, I'll also probably get a copy of the book on detailed track construction.
Also top-notch is Lance Mindhiem's Blog. His thoughts and writings have been a big influence on and reinforce the way I think about building something that I can "finish" and derive maximum enjoyment from.