The July 2004 Model Railroader Magazine had a trackplan for the Western Maryland Ry. Blackwater Division. It was a compact track plan that measured 5'3" x 9'3" and was in a Figure 8 style with 18 inch curves. You can download the pdf of the trackplan here.
The Facebook Group "Ho scale 4X8 Layout builders" had a track plan by Ed Hewitt which was kind of based on this figure 8. He did a very nice job, and though there are some differences, it kept a lot of the same ideas. There is a link to a video by him, but you must be a member of the group in order to view it. It just shows the train going around the track. From that you can see how the figure 8 works.
Here is the track plan featured in Model Railroader Magazine. It's heavy on track, and mountains hide some of the track. It look very busy, but it's kind of hard to visualize it without seeing the final result.
Ed made his track plan similar and really detailed the structures with lights inside and outside the buildings showing that lots of detail can be scrunched into a 5x9 foot space.