Some ideas that I think are outside of the wheelhouse of typical Silicon Valley thought leaders:

1) Mike Bloomberg: Talk about founding and tech development of Bloomberg Professional Service (don't talk about politics at all)

2) Judy Faulkner: Founder and CEO of EPIC systems, a large privately held Hospital EHR vendor (Epic is one of the largest and most insular tech companies in the world)

3) Jack Ma: Founder of Alibaba

4) Pierre Omidyar: Founder Ebay

5) Bill Gates and/or Steve Ballmer

6) Mark Cuban

More traditional Silicon Valley:

1) Larry Ellison: CEO of Oracle

2) Marc Benioff: CEO/Founder Salesforce

3) Paul Buccheit: Talk about gmail and early Google R&D product only

4) Matt Cutts: Get him to tell us how SEO really works

5) Scott Cook: Founder Intuit

6) Jeff Bezos: Founder/CEO Amazon

7) Tony Fadell: iPod Designer & CEO of Nest