Requests for help like this appear from time-to-time and usually draw the same responses. First, you have to be a little more specific in your "givens & druthers" (i.e. what your limitations are and what your preferences are). Examples include are you planning to run steam or diesel or a combination? What era do you choose to model? Following any specific prototype? Any particular industries you want to model? As far as power, how many trains do you want running at one time? Are you planning analog or digital control? Anyone wanting to help you will need more details of your "plan."
Second, spend more time reading this and other model railroad related fora. There is a section here (and on other fora) dealing specifically with track planning and sections dealing with electrical control of layouts. Synthesize what you learn into your own plans, even if just a rough sketch, and then others will provide advice. Another option is to hire somebody (there are many vendors) to plan and/or build your layout. Please note that even a basic around-the-walls plan doesn't have to be purely circular. With your size availability, you could run point-to-point, point-to-loop (often referred to as out-and-back) or loop-to-loop, either by way of stacked (needing an upper level) reversing loops or stacked dog-bone designs.
The combinations may seem endless, but you have to narrow it down for yourself while seeing if you can fit what you want (those druthers again) within a chosen design. Then, you will get more help.
Chuck
