Forgive me but I have to laugh - but not in a condescending way.
Our club layout is 185' x 30'. One individual loop around the layout is longer than a football field. Guess what? We have the same problem as you do with finding space for everything!
You MUST face reality and think long and hard about your list of Givens and Druthers! Givens are things you can do nothing about and MUST accept - like the size of your room, money to spend, etc. Druthers are the things you want - like a coal mine, do want loops to watch the trains run or do you want to run prototypical ops, etc. Once you narrow down your Druthers based on your Givens, the design should come easily. If you're not willing or capable to get to a list of Druthers based on your Givens just stop now and take up something else.
-Greg
P.S. It's perfectly ok to have your Druthers change after you've completed your layout and rip it down and start over. Why do you think most of us are on a layout numbered other than 1? 
