A left to right is always smaller than a top to bottom chart. I get to explain this one all the time during family reunion season. If you think about the box on a family history chart, with the name, dates and places for a person, it is usually wider than it is tall. As much as you try to squish it, that is just the way a name is written--the way our language works--horizontally. So if you utilize the height for the greatest amount of people you will get a smaller sized chart than if you use the width for the greatest amount of people. Thus a left to right chart (be it ancestors, or descendants) is always more compact than a top to bottom chart.
The place where left to right becomes most useful is in trying to compact a descendancy chart. Most people think of your regular family reunion chart as top to bottom, starting with the ancestor at the top and working with the descendants going out beneath them. With alot of people, that can get really wide, and hard to hang at a family reunion. When people are trying to save space, we can print the chart left to right and then they can turn it 90 degrees and still hang it with the ancestor at the top and the descendants going out to the bottom. You'll just have to tilt your head to read the writing. As long as you don't mind that, you'll usually save about two-thirds of the space.
A circle chart is also always most space conserving. Each box gets smaller as you move out to the last generations so you usually can't fit dates or places in and you usually use a smaller font in the outside rings. I can get 12 or 13 generations in a 42x42 circle chart, when a well filled out left to right pedigree chart can be 40 feet or so.
No matter what the style, or what the size, we can do it for you at Generation Maps.