You may want to consider the "folded dogbone" for an out and back configuration with a town or two somewhere in-between the two bone ends.
Personally, I'd run down to the local hobby shop (LHS) and buy one of the trackplanning books before I spent any money on anything else. There is probably one layout that would fit your needs. The books will have all the specifications spelled out and a list of all the different track pieces you will need. Plus, somebody else beat their brains out figuring out an interesting layout and trackplan, so you don't have to.
Throwing down track wishy washy is easy, just start. Now, if you want to make it believable and have a reason to exist, that takes alot of research( don't worry, you have a lifetime to do that) even if you make up a fictional railroad. I consider research as being just as much fun as running trains, building models or scenicing, as I would think most here do. But, you have to start somewhere and a trackplan designed by a pro will save you alot of time.
Also, the drawings of the layouts in 3/4 views are nice. Gives you a real good idea of what the layout will look like all finished(?). You'll probably spend hrs drooling over all the different layouts designs.
