The first thing to ask is what kind of track you plan to use? Some favor the older stuff because they want to maintain the authenticity; the disadvantage is that it's a real space-eater. If you are tight on space, I'd go with Flex-track. Here's a site with some layouts that are space-savers; you can add another elevated level and use turnouts to link the two levels. I'd also suggest investing in Anyrail, or at least trying out the demo so you can see what it's like. The demo is free and allows you 50 lengths of track to play with, indefinitely: http://www.anyrail.com/index_en.html Best wishes with it!
I'd second that suggestion on AnyRail. I read about it in MR about six months ago and downloaded the trial version for free. It worked great so I bought the full blown version for fifty some bucks. It works great and it's a lot easier than trial and error with real track. It's also very intuitive and easy to use. I tend to try things out without reading manuals ahead of time and I have only had to refer to the manual twice. It's that easy to use. Curving flex track took some getting used to though.