I would like this to be fairly literal. A classic-looking arch or arched bridge. However, it needs to have some aspect suggesting technology or "digitality".
I like the shape of the bridge in the attached photograph.
As a style guide, I like simple, sophisticated, old-fashioned designs. The style should be more classical than "dot com". Something that could be printed letterpress. For example, the Brooks Brothers mark (see brooks.jpeg) and Winged Warrior. They are elegant and simple and have a nice texture.
Although this is a software company, it is really a business-to-business company. The logo should give a sense of confidence, like "this arch is strong and will support a bridge, just like we will support your business".
The words "Arch" and "Digital" should both be readably sized.
If the text is below the mark, it should also be able to display on the right side for a more horizontal variation, e.g. in a web page header.