Keep it simple and accessible
Today, executives simply don’t have the time or attention to read a 20+ page document. If that’s what you give them, your Business Case won’t be read. You need to make it convenient and easy for them. First, make it easy to review anywhere, including a smartphone. Second, make it scan-able. People don’t read…they skim. Of course, you need to embed or link to the detailed source files in case the executive wants the details. But, don’t let those details drown out the primary points you want to make.