Before you put any track down, I'd suggest you play around with a computer-aided design program, like XtrkCad. It will let you try many different configurations (and save a lot of trees!) as well as letting you test-run trains on your layout, so you can check clearances as well as operating scenarios. And, it will give you a parts listing of all the track you have used. When you're ready to build your layout, you can even sacrifice a couple of trees and print a 1:1 plan of your layout, paste it on your benchwork and lay track right over it. Best of all, XtrkCad is FREE! It's got a bit of a steep learning curve, but once you've got the hang of it, you'll wonder how you ever did without it.