One of my clients is one of the finalists in a long RFP process full of long presentations, documents, meetings. After all this information, the client thought it was appropriate to send one last piece of PowerPoint: a simple recap of why they are the best choice in 10 slides.
It was probably one of the most convincing presentations of the entire process. It took very little time to write. It contained much more emotional arguments (we are fun to work with etc.) than all the previous material that was used.
The visual concept I used was designed for on screen reading. I doubled the width of the page to an aspect ratio much wider than 16:9. Reserved the entire left side of the chart for a sentence in huge fonts, and supported that sentence with a very simple picture on the right side. Just 10 pages.
PDF it, email it, and hope for the best.