Option to format top-to-bottom instead of default left-to-right

[jeffrey-aguilera]

Need to incorporate layout optimization, as this is not very helpful for any but the simplest of hierarchies.

[mikeyhu]

Scaladiagrams doesn't really deal with layout issues itself; it generates a directed graph as a Dot file that can then be processed by anything that understands Dot format. Graphviz itself includes a number of different tools that layout a graph in different ways, so these might be suitable for your purpose:
https://en.wikipedia.org/wiki/Graphviz

Dot format can also be imported by programs such as OmniGraffle so you could always post process the graph:
https://en.wikipedia.org/wiki/DOT_(graph_description_language)