Maybe a construction supply yard like this one (edit:oops, that's actually a landscaping company, but it would work too) in Waterford, MI. You'd have some bunkers for piles of sand, aggregates and other materials in the back, and maybe just a small office/shack in the front. Keeping with your trucking theme, you could have construction vehicles driving in for pickups.
Given the size of the layout, I really don't think the S curve is going to be that much of a problem. These are a major issue only if you're running long passenger cars, or cars longer than 50' with body mounted couplers. Hard to run these big cars on a 24 x36" layout...
If you stick to 40 and 50' long cars and 4 axle diesels operated at a reasonable speed, I don't think you'll ever have a problem on the mainline crossover. You might experience some hiccups backing into the yard through an S, but again, given your circumstances, I think different rules apply.
Lee
Route of the Alpha Jets www.wmrywesternlines.net
Thanks for the critique.
I have not had any problems with my track plan at all. In fact, for the first time time I became a model railroader, I hooked up one of the 16 remote switches I have on the layout and it work. I was thrilled! Before long I'm going to have all 16 hooked up and doing realistic operation!