I've done those sorts of sales talks when I was a tech consultant at Accenture and continue to do some now as a technical founder. I have also heard the pitch from vendors when I was at Accenture wanting me to bring their wares to my clients.
In the end it comes down to being able to communicate and listen well. Be an active listener and find out the problems that the C-level customer has. This could mean the actual business problem (sales needs to grow 10% and it hasnt for 3 years), logistical problems(my teams don't communicate), a political problem (I can't deploy a solution without getting the Network Solutions team invovled) - all are things 1) You should know about and 2) You may be able to fix.
That sounds simple, but it's really very hard to not get too wrapped up in what you and your company are focused on, rather than what this specific customer in front of you right now cares about. The best salespeople of ANY kind are very good at getting in synch with their customers - seeing the world, and their product from their customers POV and then seeing how their product fits into that worldview.
It's a great question, but I don't have the insight on it. My job is on the technical level, and I can just convey to you what happens in a real company.
I don't think I would be the best choice to give the talks. I'd be fine for drinks after.. I'm casually good with C Levels, but I'm a tech at heart, and having me explain things... I tend to do the bad thing of going too technical, and not realizing it before their eyes glaze over.
hmmm it seems like the key is to find the balance between evangelizing your product/vision while genuinely soliciting inputs from the C level on what their priorities are. Hopefully there will be a match somewhere in that conversation